Zool. J . Linn. SOC.,58: 1-37. With 2 plates and 8 figures
January 1 9 7 6
The defensive behaviour of Ghanaian praying
mantids with a discussion of territoriality
MALCOLM EDMUNDS*
Department of Zoology, University of Ghana
Accepred for publication March 1975
The defensive behaviour of 18 species of mantids is described and further details are given of
the defences of 12 species whose behaviour was described in an earlier paper. As a result the
defences of 3 7 genera of Ghanaian mantids are now known. Most species of Mantinae have a
general resemblance to their background and in Sphodromanris lineola and Miomantis paykullii
there is a correlation between colour of background and colour of insect. Most other species of
mantid have a highly specific resemblance t o bark, grass, sticks or leaves, and the evolution of
these insects is discussed. Fire melanism occurs in Galepsus foganus and Pyrgomanfis pallida.
Evidence is presented which suggests that the selective factor leading to reduction of wings in
females of many species is predation by birds. Ten species of mantid have first instars which
mimic ants, and in S. lineola first instars are positively associated with Oecophylla, the ant they
most closely resemble. Tamchodes afzelii not only has nymphs which resemble ants but it preys
extensively on ants as well. The functions of startle displays and the evolution of ocelli in
rnantids are discussed, and four types of territorial display which result in spacing out of
nymphs are described.
CONTENTS
Introduction
. . . . . . . . .
Descriptions of defensive behaviour
. .
Summary of defensive adaptations
. .
Discussionof primary defence
. . . .
Body colour polymorphism
. .
Leafmimicry
. . . . . .
Barkmimicry
. . . . . .
Grassandstickmimicry
. . .
Reductionof wings
. . . . .
Defence against ants and ant mimicry
Discussion of secondary defence
. . .
Function of the startle display
.
Variation in the startle display
.
Evolution of ocelli
. . . . .
Territoriality in mantids
. . . . .
Summary . . . . . . . . . .
Acknowledgements
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Note added in proof . . . . . . .
References
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Present address: Department of Biology, Preston Polytechnic, Preston PRl 2TQ.
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M. EDMUNDS
2
INTRODUCTION
The anti-predator defensive behaviour of 25 species of Ghanaian praying
mantids has been described recently (Edmunds, 1972). In this paper I report on
the defensive behaviour of an additional 18 species of Ghanaian mantids, and
further observations are also presented on several of the species described in my
earlier paper. As a result of these two papers, the defensive behaviour of 37 out
of the 49 genera of praying mantids recorded from Ghana has now been
described. The classification adopted is that of Ragge & Roy (1967) except for
the transfer of Oxypilus from the Mantidae to the Hymenopodidae (Edmunds,
1972). In addition the species which I describe here under the name
Catasigerpes occidentalis is listed by Ragge & Roy (1967) as C.toganus. The
reasons for this change of name are given under the section on this species.
Ghanaian mantids whose anti-predator behaviour has now been described are
thc following:
Family
Subfamily
Species
Amorphoscelidae
Amorphoscelis maculata *
Amorphoscelis lagrecai
Paramorphoscelis gondokorensis
Thespidae
Hoplocorypha nigerica*
Mantidae
Sibyllidae
Tarachodinae
Tarachodes afzelii *
Galepsus toganus *
Pyrgomantis pallida*
Liturgusinae
Theopompella westwoodi
Theopompella chopardi
Iridopteryginae
Negroman tis modesta *
Nilomantis edmundsi
Oxyothespinae
Oxyothespis longipennis
Angelinae
Leptocola phthisica*
Mantinae
Plistospilo ta guineensis *
Cataspilota misana
Proh ierodula orna tipenn is
Polyspilota aeruginosa *
Tenodera superstitiosa *
Sphodromantis lineola *
Sphodromantis aurea
Paraman tis prasina *
Paramantis togana
Mantis religiosa*
Statilia apicalis
Miomantis paykullii*
Miomantis aurea *
Sibylla limbata
DEFENSIVE BEHAVIOUR O F PRAYING MANTIDS
Hymenopodidae
Epaphroditinae
Phyllocrania paradoxa *
Hy menopodinae
Pseudoharpax virescens *
Chloroharpax modesta
Panurgica compressicollis
Chlidonoptera lestoni
Pseudocreobotra ocellata *
Acromantinae
Oxypilus hamatus*
A nasigerpes b ifasciata *
Catasigerpes occidentalis *
Chrysoman tis speciosa
Chrysomantis cachani
Vatidae
Stenovates strachani"
Danuria buchholzi*
Popa undata
Empusidae
Idolomorpha lateralis *
Hemiempusa capensis*
3
In this list, species whose behaviour has been described in my earlier paper are
marked with an asterisk, though for some of these further information is
presented here. Mention is also made in the text to the following Ghanaian
mantids, but their defensive behaviour has not been studied in detail:
Amophoscelis laxeretis *, Compsothespis occidentalis, Miomantis lam toensis
and Chlidonoptera chopardi?
As in my earlier paper, two types of anti-predator behaviour are recognised:
primary defensive adaptations, which reduce the probability of a predator
initiating a prey-capture attempt, and secondary defensive adaptations, which
operate only after a prey-capture attempt has been initiated and which reduce
the chances of its being successful. There are two principal types of primary
defence: a general resemblance to the background so that the insect is
camouflaged, and a highly specific resemblance to part of the environment such
as a stick or a ,leaf. These specific resemblances are here considered to be
examples of mimicry and are named in accordance with the object resembled,
e.g. stick mimicry, grass mimicry, leaf mimicry and bark mimicry. A study of
the different species of stick and grass mimics reveals that there are two very
different ways in which the resemblance can be attained, so it is useful to
distinguish short stick and grass mimics from long stick and grass mimics. The
evolution of these different forms of mimics is discussed in this paper.
In the terminology of Cott (1940) all of the mantids described here are
cryptic, not mimetic. Resemblance to a plant, such as a stick, implies crypsis,
whilst resemblance to an animal implies mimicry. However, the resemblance to
a stick or a leaf can be very precise and hence comparable in morphological
specialization to mimicry of another animal. Wickler (1968) and Edmunds
(1974) define batesian mimicry in terms of its effects on a signal receiver,
which in this context is the predator. Following Wickler, if an animal produces
a counterfeit signal which deceives a signal receiver, this is mimicry. Cryptic
animals rely for protection on producing few or no signals, hence they are not
4
M. EDMUNDS
easily found by predators. Mimetic animals, by contrast, are detected by
predators, but the signals which they produce cause the predators to refrain
from attacking them. This distinction may be valid in theory, but since we
know so little about how predators recognise prey it breaks down in practice.
Thus if one accepts this distinction, then stick mimics and leaf mimics are
probably truly mimetic since they rest fully exposed to a predator, but are not
apparently recognised as being insects. Bark mimics, however, merge into their
background, and hence they are simply extreme examples of crypsis. But it is
very difficult to decide if grass mimics such as Leptocola and Pyrgomantis are
mimetic or cryptic: we just do not know what predators perceive when they
encounter such a mantis in a natural situation. In this paper therefore I have
called all forms of extreme resemblance “mimicry”, although it should be
understood that the principles by which the animal escapes being eaten may
not be the same in all cases.
Secondary defensive adaptations include active escape by running, jumping
or flying, death feigning (thanatosis), startling or frightening displays, and overt
attack to which all species resort when seized by a predator. In the discussion
at the end of this paper consideration is given to the function and evolution of
displays: whilst many displays function to intimidate potential predators,
displays may have other functions as well, for example, spacing out individuals.
Several species of mantid exhibit some form of territorial behaviour which
results in spacing out of individuals and hence lessens the chances of
cannibalism occurring, and this form of behaviour is also discussed.
Observations are also reported on the defences of nymphs and these include a
survey of ant mimicry amongst first-instar mantids.
DESCRIPTIONS OF DEFENSIVE BEHAVIOUR
1. Amophoscelis lagrecai Roy, 1964
Two females examined. A forest species. Arboreal.
Primary defence. A greenish brown, mottled, dorsoventrally flattened mantis
which lives on tree trunks as do other species of the genus (see Edmunds,
1972).
Secondary defence. When poked both insects ran quickly or flew, as did
A . maculata Roy (Edmunds, 1972). No startle display could be elicited.
2. Paramorphoscelis gondokorensis Werner, 1907
Two males examined. A savanna species. Judging from its colour and resting
posture it is probably arboreal.
Primary defence. This species is grey (becoming browner when pinned),
elongated, and is a short-bodied stick mimic with similar defences to the short
grass mimic Pyrgomantis (Edmunds, 1972). When placed on a stick it rests with
the body closely apposed to the stick and the legs held close to the body. The
head is held in the prognathous position with the mouthparts directed forwards
(Fig. 1). Thus the head and body taper gradually to the stick and there is no
conspicuous recognition mark by which a predator lateral to the mantid might
DEFENSIVE BEHAVIOUR OF PRAYING MANTIDS
5
Figure 1 . Primary defence posture of male Paramorphoscelis gondokorensis: a short-bodied
stick mimic. Drawn from a colour transparency.
recognise that a mantid is there. The head also has two posterior projections
which conceal the neck from dorsal view. Paramorphoscelis rests either with
the head upwards or downwards.
Secondary defence. When disturbed Paramorphoscelis usually runs up the
stick or dodges round to the other side and then becomes motionless, just as
does Pyrgomuntis. It may also fly, especially in the unnatural situation of being
disturbed when on a flat surface rather than on a stick. There is no startle
display.
3. Hoplocorypha nigerica Beier, 1930
One female examined. The defences of the male have already been described
(Edmunds, 1972).
Primary defence. The female is a grey-brown stick mimic with long legs and
two projections on the back of the head to conceal the neck from dorsal view,
just as in the male, but with a much fatter abdomen. There is a mid-dorsal
black line on the abdomen. When disturbed the male protracted the forelegs so
as to increase the resemblance to a stick, but this occurred only very rarely in
the female.
Secondary defence. When poked the female ran or hopped, just as did the
male, but since she is apterous, she cannot fly. The foreleg femora are black on
6
M. EDMUNDS
the inner surface, and the ventral surface of the thorax is crimson, suggesting
that these colours may possibly have significance in some display, but no
display was ever seen. They are unlikely to be flash colours since they are not
easily visible when the mantis moves.
4.Theopompella westwoodi (Kirby, 1904)
One male examined. A forest species. Arboreal.
Primary defence. This mantis is dorso-ventrally flattened with the forewings
having the coxal area angled from the rest of the wing and normally lying
lateral to the abdomen when at rest. In this way the contour of the insect is
smoothed from either anterior or posterior view, and any lateral shadow is
obscured (Fig. 5 , Plate 1B). The insect rests on tree trunks, most usually with
the head facing downwards. As in Taruchodes, the forelegs are held slightly
abducted so that they too smooth the contour from head to substrate, but the
head is in the prognathous position with the mouthparts directed forwards,
unlike Turachodes. The body and wings are mottled with dark brown, pale
brown and cream, and there are disruptive bands on the forelegs, so the insect
is a bark mimic.
Secondary defence. When disturbed Theopompella runs or tries to fly, or it
may slash with the forelegs at the object attacking it. No startle display was
seen, but the forelegs are brightly coloured on their inner (ventral) surface: the
coxa has a dark brown spot proximally, and is then cream merging to mauve
distally; the femur is mostly dark brown with a cream band followed by brown
and then white distally; the tibia is cream with a mauve band half-way along its
length. This colour must have some function, though it need not be in a startle
display.
5. Theopompella chopardi Roy, 1963
One male examined. A forest species. Arboreal.
Primary defence. The resting posture of this species is exactly as in
T. westwoodi with prognathous head, slightly abducted forelegs, and wings
concealing lateral shadow. If disturbed it flattens itself still more closely t o the
bark.
Secondary defence. When poked it opened its wings as if about to fly, but it
did not display. The wings are transparent with purple-brown and white veins,
except that the bases of the hind wings are grey. The abdomen is dark brown
dorsally. This lack of bright colours further suggests that no startle display
occurs in this species.
6. Nilomantis edmundsi Roy, 1975
Numerous males examined. A savanna species. Probably arboreal.
This species is very close toNilomuntis floweri, Werner 1907, from East Africa,
Arabia and Sudan (Roy & Leston, 1975).
Primary defence. This is a very small species with bright green body (18 mm
long, but with wings protruding a further 2-3 mm) and legs. (The legs become
DEFENSIVE BEHAVIOUR O F PRAYING MANTIDS
7
yellow in pinned insects.) There is a yellow stripe mid-dorsally on the thorax
and also on the abdomen, but this latter is normally hidden by the pale green
wings. Thus the mantis has a general resemblance to green vegetation.
Secondary defence. When disturbed this species almost invariably flies away.
One male, however, was observed to give an alternate left and right “boxing”
display, similar to that of Cutasigerpes (Edmunds, 1972), with both legs
extended synchronously first to the left, then to the right. No startle display
was observed. I t is not known if this boxing occurs regularly in Nilomantis, and
if so whether it should be regarded as a defensive response or if it has some
intraspecific function as in Oxypilus and Catasigerpes.
7 . Oxyothespis longipennis Chopard, 1941
One male examined. A savanna species which probably lives amongst grass.
Primary defence. An elongated grass mimic with long legs and no unusual
resting posture (Fig. 2). It is buff in colour and highly cryptic on dead grass.
The forelegs are often held slightly protracted, but not in line with the head as
occurs in Hoplocorypha.
Secondary defence. When disturbed Oxyothespis either remains almost
motionless (i.e. moving minimally to one side or downwards to avoid being
poked) or it flies. The wings are transparent and there are no bright colours on
the feeble forelegs, so probably there is no startle display in this species.
The related Compsothespis occidentalis Sjostedt, 1930, is another elongated
brown mantid with even more feeble forelegs than Oxyothespis (see fig. 30 of
Gillon & Roy, 1968). I t has the head and thorax shaped so as to conceal the
neck from dorsal view (as in Danuria and Hoplocorypha described by
Edmunds, 1972), and it is probably an arboreal stick mimic. The hind wings,
h
Figure 2. Primary defence posture of male Oxyothespis longipennis: a long-bodied grass mimic
with no unusual cryptic posture. Drawn from a colour transparency.
8
M. EDMUNDS
however, are orange basally and black distally suggesting their use either in a
display or (more likely) as flash colours. Unfortunately the only specimen
available to me was moribund when found.
8. Leptocola phthisica (Saussure, 1869)
One female examined. The defences of the male of this common grassland
species have already been described (Edmunds, 1972).
Primary defence. The female rests amongst long grass, as does the male, with
no particular cryptic posture (Fig. 3).
Secondary defence. Unfortunately the insect was unhealthy and had a
broken leg, so it was not possible to examine its responses at all adequately to
being attacked. When seized with fingers it retaliated by scratching with the
forelegs, but no startle display could be elicited. However, the wings are
reduced to very small erectile organs, quite useless for flying, but of possible
use during a startle display. The forewing is mauve with a green costal area,
whilst the hind wing is greenish-white proximally with a black spot
posterodistally. This striking colour suggests that the wings may be erected in
display, either to a conspecific or to a potential predator, and the resemblance
Figure 3. Primary defence posture of female Leptocolu phthisicu: an extremely elongated grass
mimic with no unusual cryptic posture. Drawn from life. Inset: details of colour pattern on
wings which may perhaps be used for secondary defensive display.
DEFENSIVE BEHAVIOUR OF PRAYING MANTIDS
9
of the black spot to an eyespot suggests that such a display is directed against
predators (see Fig. 3, inset). Therefore it is probable that, as with Turachodes
and Dununu, the wings have been reduced in the female because they are an
easily recognisable visual cue to predators, but they have been retained as small
brightly coloured structures because they are of protective value during a
startle display.
9. Plistospilota guineensis Roy, 1965
The behaviour of a single male of this species has already been described
(Edmunds, 1972 p. 8 & pl. l ) , but the caption to the plate illustrating its
display incorrectly refers to it as a female. A second male has now been
examined: when poked it either gave a startle display or it flew.
10. Cutuspilotu misunu (Giglio-Tos, 191 1)
Two males and two females examined. A forest species. Arboreal.
Primary defence. The adult insect is mottled grey and dark brown with a
green costal area to the forewing. I t is thus cryptic on branches and trunks of
forest trees. When disturbed the adult occasionally lowers the body towards the
substrate and protracts the forelegs in front of the head, just as do the stick
mimics Dununa and Hoplocoryphu.
Secondary defence. When poked, males usually run or fly, females run. Only
occasionally did the two females give a startle display with the forelegs
abducted, the hind wings raised, and sometimes with stridulation. There are six
prominent cream spots on the forecoxa which is orange proximally, merging
into brown distally. The hind wings are mostly black with three yellow bars
anteriorly. Hence although the display was not often given it is quite dramatic.
11. Prohierodula omatipennis (Bolivar, 1893)
One male and one female examined. A forest species. Arboreal.
Primary defence. The female is bright green, very similar in appearance to
Sphodromantis lineola, whilst the male has green head, thorax, legs and coxal
area of the forewing, but the rest of the forewing is brown mottled with black.
Both sexes are thus cryptic with a general resemblance to vegetation.
Secondary defence. When poked the male ran, flew, or gave a startle display,
and the female ran or gave a display. The forefemur is yellow with two black
spots whilst the coxa has 6 or 7 cream spots. The hind wings are mostly black
with a crimson or bright magenta coxal strip, large bright orange spot at the
wing tip, and two clear spots just behind the crimson region. Hence the startle
display is one of the most dramatic of any Ghanaian mantis. In addition the
abdomen is pink dorsally with a middorsal black line.
12. Sphodromantis aurea Giglio-Tos, 1917
One male and one female examined. A forest species. Arboreal.
Primary defence. Both animals were bright green like Sphodromantis lineola
10
M. EDMUNDS
(see Edmunds, 1972), and hence they have a general resemblance t o green
vegetation.
Secondary defence. When poked the male always flew, the female gave a
startle display. The three or four creamy white spots on each forecoxa are very
large and conspicuous, and there is also a large blue-black or greenish black spot
on the forefemur, so that with the legs abducted and held close together the
spots resemble eyes (Plate 1A). During display the red jaws are also visible and
yellow marks intersegmentally on the ventral surface of the abdomen can
sometimes be seen. The female is slightly larger than is the female of S. lineola,
and the display, with brighter marks on the forelegs, is more conspicuous.
13. Paramantis prasina (Serville, 1839)
One male examined. The defences of two animals of this species have been
described in Edmunds (1972), but these were females, not males as stated in
that paper.
Primary defence. The male is green with purplish brown stripes mid-dorsally
and at the edges of the pronotum, as well as on the posterior margin of the
head. The posterior half of the pronotum is also purplish brown, and so also are
the wings except for the green costal areas. Thus the male is much browner
than the female which is entirely bright green in dorsal view. Both sexes have a
general resemblance to vegetation.
Secondary defence. When poked the male ran, flew or gave a weak display
involving the forelegs but not the wings. Since the forecoxa has bright red spots
this display is quite dramatic. The hind wings are suffused purplish grey and the
abdomen is crimson dorsally suggesting that the wings may sometimes be raised
during display, or that these are flash colours.
14. Paramantis togana (Giglio-Tos, 1912)
One male and one female examined. A forest species which occurs
occasionally in the savanna (e.g. Kwabenya, near Accra). Probably arboreal.
Primary defence. The male is brown with green eyes, the female is green.
Both are therefore camouflaged on vegetation.
Secondary defence. When poked the insects either ran, flew or gave a startle
display. During display the female abducted the forelegs but did not raise the
wings whilst the male displayed both legs and wings. This is probably individual
rather than sexual variation since normally females of mantids display far more
readily than males. The forelegs each have three large yellow spots on the coxa,
the jaws are black, and the wings are brightly coloured as follows: hindwing
mostly black with yellow veins, but with the costal area crimson; undersurface
of forewing mottled red and yellow (hence appearing orange), but crimson and
grey proximally, transparent posteriorly, and with conspicuous yellow and
crimson bars anteriorly in the costal region. Hence the display is very dramatic.
15. Statilia apicalis (Saussure, 187 1)
One male examined. Mainly a forest species but also occasionally found in
the savanna at Legon. Probably arboreal.
DEFENSIVE BEHAVIOUR O F PRAYING MANTIDS
11
Primary defence. A dark brown mantid with a general resemblance to twigs
or sticks.
Secondary defence. When poked the insect ran, flew, or displayed. The
display always involved erection of the hind wings, usually with stridulation.
Sometimes the forelegs were held in the abducted position close to the body,
thus displaying their bright colours to the full, whilst at other times they were
held t o one side as in Hemiempusa (Edmunds, 1972). The wings are suffused
brown but are transparent, as in Polyspilota, whilst the forelegs have two cream
spots distally on each femur, one cream spot proximally on each coxa, the rest
of these regions being bluish black with small yellow spots (see Plate 6 of
Edmunds, 1974). The ventral surface of the thorax is red anteriorly, bluish grey
posteriorly, so the displaying mantis is very impressive.
16. Miomantis paykullii Stil, 1871
One brown and two green females were examined in addition t o those whose
behaviour has already been described (Edmunds, 1972). These insects did give a
slight display when poked, with erected hind wings, but without abduction of
the forelegs. The hind wings are pale yellow, and the posterior surfaces of the
forewings are also pale yellow. The abdomen is orange-yellow dorsally, possibly
as a flash colour. None of these or of the earlier insects could be induced t o fly,
either when poked or when thrown into the air.
17. Miomantis aurea (Giglio-Tos, 1917)
A second female of this species was examined. Unlike the first individual (see
Edmunds, 1972), it did not display, but ran or jumped when poked.
18. Sibylla limbata Giglio-Tos, 191 5
Two males examined. A forest species. Arboreal.
Primary defence. The normal resting posture of this species is upside down
so the head and pronotum are reverse countershaded, dark brown ventrally,
more yellow-brown dorsally. The legs and abdomen are dark brown, but there
are cream spots at the bases of legs two and three. The wings are pale green
with brown veins. There are foliations on legs two and three, the head has an
irregularly shaped vertex, and the pronotum is long and narrow. It is not
known if this species normally rests on branches or on leaves, but obviously it
is cryptic.
Secondary defence. When poked the insects ran or flew. No display was
observed, and since the forelegs have no conspicuous markings it is probable
that they do not display.
19. Phyllocrania paradoxa Burmeister, 1838
An additional male and female were examined which enable me to add to
my previous description. The female is pale straw in colour in contrast to the
previous female which was dark brown (Edmunds, 1972). This female is
illustrated in colour in Edmunds (1974: plate 3). Neither insect gave a display
12
M. EDMUNDS
although the basal region of the hind wing is blackish, suggesting that a display
may possibly occur under some circumstances.
20. Chloroharpax modesta (Gerstaecker, 1883)
One female examined. A forest species. Presumed to be arboreal though the
present individual, collected as a first or second instar nymph, was found on a
shrub in secondary forest.
Primary defence. The female is green with a black-rimmed yellow spot on
the forewing, and black marks dorsally on the head and thorax (Fig. 7, Plate
1C). It probably has a general resemblance to vegetation, but it is not known if
this spot is only of use in display or if it is disruptive.
Secondary defence. When poked it attempted to run, jump or fly, but on
two occasions it gave a startle display. The display posture is similar to that of
Miomantis aurea and of Pseudocreobotra (Edmunds, 1972) with the wings
raised and the forelegs held extended and partially abducted. The small spots
on the wings are then visible and could possibly be mistaken for small eyes,
though they are nothing like as dramatic as the eyespots of Pseudocreobotra or
Chlidonoptera The hind wings are white, but there are no conspicuous colour
marks on the forelegs.
2 1. Panurgica compressicollis (Saussure, 1898)
Two females examined. A forest species. Probably arboreal.
Primary defence. The body and wings are mottled with various shades of
brown and purplish brown. The normal resting posture of this short and broad
mantid is upside down with the legs held close to the body and the wingtips
practically touching the substrate posteriorly. The result is that the insect
closely resembles a folded dead leaf (Plate 2A). If the twig is moved the insect
pivots on its legs and sways laterally, just as if the leaf is about to break off
from the twig.
Secondary defence. When disturbed both insects either attempted to run,
jump or fly, or they gave a startle display or struck at the stimulus source with
the forelegs. The startle display posture is similar to that of Chloroharpax and
Pseudocreobotra, with the forelegs extended laterally, and the wings opened. It
may be directed either frontally or laterally. The inner surface of the forelegs is
black with pale yellow spots. The hind wings are crimson-red basally and along
the anterior edge, but this merges into black posterodistally with yellow veins.
The under surface of the forewings is also tinged with crimson, and the
abdomen is orange mid-dorsally. Hence the display is very dramatic.
22. Chlidonoptera lestoni Roy, 1975
One male examined. A forest species, but whether from the canopy, shrubs
or herbs is not known. This species is closely related to C. vexillum from the
Cameroons and is fully described by Roy & Leston (1975).
Primary defence. The insect is disruptively marked with green and yellow
with a large eyespot on the forewing. Although this eyespot can be conspicuous
DEFENSIVE BEHAVIOUR OF PRAYING MANTIDS
13
during display I consider that it is not conspicuous during normal resting when
the insect is on vegetation or flowers (Fig. 7).
Secondary defence. When the mantid was poked it tried to run, fly or give a
startle display. The display is very similar to that of Pseudocreobotra ocellata
(Edmunds, 1972), but the sub-circular eyespots are much less perfect
imitations of a vertebrate eye. The basal half of the otherwise transparent hind
wing is orange.
A single female was also examined, but unfortunately it was moribund and
soon died. The female has larger, more circular eyespots than the male (Fig. 7,
Plate 2D), as do other species of Chlidonoptera (Roy, 1964, 1965). The hind
wings were yellow with red spots, very like those of C.vexillurn, so its display
must be very dramatic.
23. Pseudocreobotra ocellata (Beauvois, 1805)
Two further females were examined which enable me to add to my previous
description (Edmunds, 1972). During display both sexes erect the hind wings,
but whilst in the male these are entirely transparent with white veins, in the
female the proximal half is yellow, the distal half transparent. The forelegs may
be extended anterolaterally in display (as shown in Edmunds, 1972: plate l),
or they may be held in the normal resting position.
24. Oxypilus hamatus Roy, 1966
Two females examined. The behaviour of the more easily obtained males has
been described earlier (Edmunds, 1972).
Primary defence. The female is entirely brown and completely apterous. She
has a general resemblance to twigs but has no specialized resting posture such as
occurs in Catasigerpes or Danuna.
Secondary defence. When disturbed the insects either ran or jumped, but
they never gave a startle display.
25. Anasigerpes bifasciata Giglio-Tos, 1915
One male and one female were examined which enable me t o add to the
description given earlier (Edmunds, 1972). The wings of the male are truncated
posteriorly, just as they are in male Catasigerpes, Phyllocrania and Panurgica, so
that when at rest the wing tips touch the substrate. In this way the insect
resembles a short twig arising from the branch on which it is resting. The dorsal
surface of the abdomen is coloured in both sexes, orange in the male but mauve
in the female. Probably these are flash colours since no startle display was ever
seen.
26. Catasigerpes occidentalis (Wood-Mason, 1879)
One additional female was examined. The females described and illustrated
by Edmunds, 1972, as Gztasigerpes toganus are actually C. occidentalis
(identified by R. Roy). The species of Catasigerpes from the C6te
14
M. EDMUNDS
d'Ivoire-Ghana-Nigeria region are in a state of confusion, as discussed by Gillon
& Roy (1968). Females with a long vertex correspond with the type of
C. occidentalis (Wood-Mason, 1879), whilst those with a short vertex
correspond with the type of C. nigericus (Giglio-Tos, 1915). All males appear
to correspond with the type of C. toganus (Giglio-Tos, 1915), which has a short
vertex. Numerous males have now been examined but so far it has not proved
possible t o distinguish those of C. occidentalis from those of C. nigericus,
hence, if the female is unknown, males are conveniently referred t o as
C. toganus. Since the female Catasigerpes from Legon are all clearly
C. occidentalis, the males which were reared from them (Kumar, 1973) as well
as those caught at Legon must also belong to this species. Hence the correct
name for the Catasigerpes described by Edmunds (1972) and listed in Ragge &
Roy (1967) as C. toganus should be C. occidentalis.
Secondary defence. Two points need t o be added to my earlier account: the
hind wings of the female are black, which may possibly add to the flash effect
of the red abdomen when the insect flies; and one of the females exhibited
thanatosis for a few seconds after repeated poking.
27, Chrysomantis speciosa Giglio-Tos, 1915
One female examined. A forest species. Probably arboreal.
Primary defence. The face, pronotum and outer surface of the forelegs are
greenish white; the wings are mottled with shades of grey and are truncated
posteriorly as in Anasigerpes and Catasigerpes. The resting place of this species
is not known but its very pale colour indicates that it must live either on bark
or twigs. The second and third legs have minute foliations which presumably
break up their outline.
Secondary defence. The insect was unfortunately sluggish and unreactive
when first examined, and it died soon afterwards. The inner surface of the
foreleg is black with cream spots distally on the femur. It is likely that these
marks are exposed during a boxing display similar to that of Chrysornantis
cachani and of Catasigerpes.
28. Chrysomantis cachani Roy, 1964
One female examined. A forest species. Probably arboreal.
Primary defence. The dorsal surface is greyish mottled with darker brown
and with a transverse brown bar on the wings. There is also some green on the
eyes and wings. The outer surface of the foreleg is grey-brown and greenish
grey. The wings are truncated posteriorly as in Anasigerpes and Catasigerpes.
Legs two and three are minutely foliaceous. The insect is therefore cryptic on
greyish-brown twigs.
Secondary defence. When poked the insect usually tried to fly. The hind
wings are transparent and the dorsal surface of the abdomen is blackish brown,
so there do not appear to be any flash colours. No startle display was seen.
When resting or if slightly disturbed the mantis gave a boxing display similar to
that of Catasigerpes. The forelegs were extended forwards at an angle of about
45" to the midline, first to one side, then to the other. Sometimes both legs
DEFENSIVE BEHAVIOUR OF PRAYING MANTIDS
15
were extended simultaneously, first to the right then to the left; at other times
the legs were extended alternately. The inner face of the foreleg is black with
white distally on the coxa and orange proximally on the femur, so these marks
are conspicuous during the display. By analogy with Oxypilus and Cutasigerpes,
this boxing is probably a territorial, not a defensive display (Edmunds, 1972).
29. Dunuria buchholzi Gerstaecker, 1883
Numerous males and three more females enable me t o add to my earlier
description of the defences of this species (Edmunds, 1972).
Secondary defence. When the insect was poked at with forceps, it often
dodged to one side and so avoided being hit. The movement is simply one of
flexing the legs on one side so that the body is moved quickly sideways, but the
position of the tarsi on the substrate remains unchanged. One male also
exhibited thanatosis when repeatedly poked and roughly handled. The startle
display is very variable: sometimes the forelegs remain extended as in the fully
cryptic posture, sometimes they are flexed as in Polyspilotu or Sphodromantis. The tip of the abdomen is often repeatedly reflexed over the back
during display, possibly resembling a scorpion.
In the female the wings are very short, useless for flying, but still used during
startle display since the lower surface of the forewing is red and the hind wing
is black. However, none of the females examined gave a sustained display with
the short wings held open such as occurs in the similarly brachypterous
Turuchodes female which often sustains a startle display for 10 or more
seconds. In Danuriu, after much poking, the wings may be opened and closed
several times in rapid succession, or if a leg is seized they may be held open for
perhaps two or three seconds. Hence it appears that the display is designed to
startle a predator into quickly releasing it by sudden appearance and
disappearance of bright colours whereupon the mantis once again resembles an
innocuous stick. In Turuchodes, on the other hand, the display may actually be
intimidating to the predator.
30. Popu undatu (Fabricius, 1793)
Two males examined. A savanna species. Arboreal.
Primary defence. Popu is of typical shape (i.e. similar t o Mantis) but
resembles Dunuriu in its defensive adaptations. The insect is greyish brown. The
head is prognathous with two projections posterolaterally which conceal the
neck (as in Danuriu). The forecoxa is notched so that when the forelegs are
protracted anteriorly the head fits into the notch, and the profile of body, head
and forelegs resembles that of an attenuated stick (also as in Dunuriu)
(Plate 2C). The wings are truncated posteriorly, as in Cutasigerpes. The legs are
much shorter than are those of Dunuriu so that when resting the tips of the
wings often touch the substrate so that the body resembles a branch arising
from the substrate. finally the second legs have a small frill, presumably to
break up the outline. Thus this mantis is a stick mimic which has many of the
adaptations of the extremely elongated and long-legged Dunuriu, but it also has
similarities to the short-legged stick mimics such as Catusigerpes and Chryso-
M. EDMUNDS
16
mantis. I t is related closely to Danuriu and therefore gives an indication of how
the elongated stick mimics may have evolved.
Secondary defence. When the mantis was slightly disturbed the forelegs were
protracted into the fully cryptic posture, as described above. On more sudden
disturbance the mantis flew. Occasionally it gave a brief startle display exposing
pink on the lower surface of the forewings and black on the hind wings. The
forelegs were not flexed during display, but since the forecoxa is pink with
black and brown spots, it is probable that in some circumstances the forelegs
are exposed during a startle display.
Table 1. Summary of defensive adaptations of Ghanaian mantids
+ indicates a particular behaviour or characteristic occurs; - indicates i t does
not occur; ? indicates that there is some uncertainty-see text for detail. A
blank indicates no observations were made
Genus
General
Special
Runs Flies
resemblance resemblance d P
dQ
(mimicry)
Amorphoscelis
bark
Poromorphoscelis
short stick
Hoplocorypho
long stick
Torochodes
bark
Golepsus
short grass
Pyrgomon tis
short grass
Theopompella
bark
Negromantis
green
Nilomantis
green
Oxy o thespis
longgrass
Leptocola
long grass
Plistospilota
grey-green
Catospilo to
grey-bro wn
Prohierodulo
greenbrown
Polyspilota
greenlbrown
Tenodero
greenlbrown long grass
Sphodromantis greenbrown
Poramantis
green or brown
Mantis
greenlbrown
Statilia
brown
Miomantis
greenhrown
Sibyllo
green &brown
Phyllocrania
leaf
Pseudoharpax
green
Chlorohorpax
green
Panurgica
leaf
Chlidonoptera
disruptive
Pseudocreobotro disruptive
Oxypilus
brown
Anosigerpes
short stick
Ca tasigerpes
short stick
Chrysomantis
short stick
Sten o vo tes
long stick
Danuria
long stick
Pop0
stick
Idolomorpho
long grass
Herniempuso
long grass
++
+
++
++
+
++
+
+
--?
+
-
++
++
++
++
++
++
++
+
++
+
++
++
+
+
+
++
++
++
++
+
--
++
-
++
++
Thanatosis Flash Startle Wings
d Q reduced
in Q
++
+
+++
+-
+
+
+
+
++
+-
+++
++
++
++
++
+
++
++
+-
+
+
+
++
+-
++
++
+
--
+-
+
++
++
+
--
-
Boxing
display
DEFENSIVE BEHAVIOUR OF PRAYING MANTIDS
17
SUMMARY OF DEFENSIVE ADAPTATIONS
The defensive adaptations of the 37 genera of mantid described in this and in
my earlier paper (Edmunds, 1972) are summarized in Table 1. No attempt has
been made to indicate the probability of a particular response occurring, but in
general small species run or fly and rarely or never give a startle display,
whereas large species are more likely to display than to attempt to escape
actively. Question marks indicate that there is some uncertainty about a
particular behaviour; for example there are several mantids which have brightly
coloured dorsal surfaces to the abdomen which could be flash colours. Since it
is not easy to prove their function I have put a question mark in the
appropriate space.
DISCUSSION OF PRIMARY DEFENCE
Body colour polymorphism
In my earlier paper (Edmunds, 1972) I attempted to show that there is a
correlation between the frequencies of green and brown morphs of
Sphodromantis lineola and Miomantis paykullii and the colour of the
surrounding vegetation. Further data confirm the conclusions reached at that
time. For S. lineola I now have a sample of 684 males examined between
November 1967 and August 1973 at Legon. Brown insects only occur in the
dry season (October to March), apart from a single insect on 18 April 1972,
and if the data are summed by month the browns reach a peak in January
which is normally the driest month of the year (Table 2). It is possible that the
Table 2. Numbers of green and brown Sphodromantis lineola caught at Legon per month, 19671973
Month
Green
Brown
%brown
January
34
64
39
45
79
117
38
13
18
60
99
65
3
1
8.1
1.5
February
March
April
May
June
July
August
September
October
November
December
0
1
0
0
0
0
0
1
4
2
0
2.2
0
0
0
0
0
1.6
3.9
3 .O
single brown insect in April had survived since February, or (more likely) it had
spent its last few days before the final moult in a building where light
conditions tend to produce a high frequency of browns. Barnor (1972) has
shown that the most important factor determining whether a nymph of
S. lineola becomes green or brown at the next moult is light intensity. Nymphs
2
M. EDMUNDS
18
commonly occur on small trees and shrubs which are always green in the wet
seasons but which normally lose their leaves and then flush with new growth in
the dry season. A green nymph on a tree that loses its leaves will be very
conspicuous, and selection would naturally favour any insect that could
become brown at this time and then green again once the new leaves had
opened. Loss of leaves means that the tree will be exposed to greatly increased
incident light and this induces insects to become brown at the next moult. As
the leaves grow again the light reaching the insects is reduced so they are
induced to become green at the next moult. This is speculation, but it does
accord with experimental evidence and also with the observable fact that
brown insects are never very numerous: this is because leaf fall and flushing are
not synchronous on all trees but are spread over a long period of the dry
season.
In Miomantis paykullii the situation is rather different. In my earlier paper,
on the basis of six dry and one wet season samples, I concluded that colour is
correlated directly with rainfall: 70% of the population were green in the rainy
season whilst from 70% to 90% were brown in the dry season. I now have
samples of Miomantis collected monthly from 1970 till 1973. Figure 4 shows
5
?!
40
20
-
0
0- 2
3-4
5- 6
7- 9
10 - 17
Rain days per month
Figure 4. Relationship between rainfall (as number of days on which rain fell per month) and
body colour (as % of population which were green) of male Miomantis paykullii at Legon,
Ghana. The marks to the right of each block are the monthly figures on which the means are
based.
that there is a very strong correlation between percentage of green insects and
number of days on which rain fell in that month: in months with 0-2 days of
rain, only 24% of mantids were green whilst in months with 10 or more days
rain, 69% of insects were green. Using the Spearman rank correlation test
(Siegel, 1956), the correlation between number of rainy days and percentage of
green insects in that month is significant at the 0.01% level (rs = 0.65 for
N = 30). If the percentage of green Miomantis is compared with the number of
rainy days in the preceding month, the correlation is even more significant
(r, = 0.74 for N = 30), presumably because the mantids can only respond to
DEFENSIVE BEHAVIOUR OF PRAYING MANTIDS
19
change in humidity at the next moult which may be a week after the rain, and
because once adult they cannot change colour during the week or more that
they live. Miomantis lives amongst grass which changes colour according to
rainfall: if there is a drought the grass becomes brown, and if there is rain it
becomes green. Barnor (1972) found that in this species, unlike in
Sphodromantis, relative humidity is of more importance than light in
determining the colour of the insect at its next moult. High humidity induces
an insect to become green, low humidity induces it to become brown. Since
humidity of the grass is likely to correlate with its colour it is obviously
biologically advantageous for humidity to determine the colour of the insect at
its next moult. Conversely with Sphodromantis, humidity does not determine
times of leaf fall and flushing of trees (at least not in a simple way), so again it
is obviously more advantageous to use some factor other than humidity to
determine the colour of the insect. For both species, the colour is likely to
coincide with that of its surroundings, so both are likely to be camouflaged. In
addition Barnor (1972) found that when given a choice between brown and
green backgrounds, green Miomantis showed a significant preference for resting
on green whilst brown Miomantis showed a significant preference for brown
(summarized by Edmunds, 1974). In Sphodromantis, green insects choose to
rest on green leaves rather than on brown ones, but brown insects appear to
have no such preference: indeed they may even prefer green (the figures do not
differ significantly either from random or from the choice of green insects).
Since brown Sphodromantis occur rarely, and since they are likely to occur
only on entirely leafless trees (see above), they are not likely to have much
choice of resting place, so selection has not favoured the evolution of a
matching response.
Table 3. Numbers of green and brown Mantis religiosa and Tenodera superstitiosa caught at Legon in wet and dry seasons
Species
Mantis religiosa
Tenodera superstitiosa
Colour
Wet season
Dry season
brown
green
%brown
10
26
14
42
10
15
82
brown
green
%brown
41)
P
4.40
<0.05
72
2
5
88
94
not significant
Mantis religiosa also has a green-brown polymorphism, 60%of insects caught
over a four year period being brown. If the year is divided into a wet six month
period (April to September) and a dry period (October to March), there are
significantly more greens in the wet season than in the dry (Table 3). This wet
six months includes the major rains in June and the small rains of September.
August is normally dry, but no insects were caught in this month. The dry six
months includes October and March which can be fairly wet in some years. If
the same is done with the grass-living Tenodera superstitiosa the figures are not
significant, possibly because of the low frequency of green insects at all
M. EDMUNDS
20
seasons. In this species the brown form always has a green costal area to the
forewing so it is disruptively cryptic, and since even in the rainy season there is
always some dead, brown grass, selection may not have favoured such a marked
seasonal change in frequency of the two morphs.
Seasonal changes in the frequencies of green and brown forms of forest
species such as Polyspilota aeruginosa and Prohierodula ornatipennis have not
been studied but would be of considerable interest since there can be very
much less change in colour of vegetation there than in the savanna. In
Polyspilota at Legon brown males are rare; only 2 out of 31 males seen were
brown (the rest being “bicoloured” green and brown), but 5 out of 7 females
were brown. All but 4 of these insects ( 1 green female, 2 bicoloured males and
1 brown male) were caught in the dry six month period.
Another type of colour change which is probably environmentally induced is
fire melanism. Many species of grasshoppers moult into black forms shortly
after bush fires, and these are obviously better camouflaged than green or
brown insects on the blackened ground (Hocking, 1964). Fire melanism also
occurs in the mantids Galepsus toganus and Pyrgomantis pallida (Table 4). In
Pyrgomantis melanics have only been found in January and February, the end
of the dry season when bush fires are most numerous, whilst in Galepsus a few
black insects have also been taken as late as June. I t is not known if these were
long-lived individuals, or if they were induced to turn black by late burning, or
if they arose for some other reason.
Table 4. Frequencies of melanics amongst male Galepsus
toganus and Pyrgomantis pallida attracted to light at
Legon between November 1970 and August 1973
Month
January
February
March
April
MaY
June
July
Aug-Oct
November
December
Galepsus toganus
Pyrgomantis pallida
melanics
total
% melanic melanics
total
% melanic
caught
caught
10
14
9
13
8
16
10
36
33
15
13
13
0
7
0
4
8
5
0
0
1
5
3
2
1
2
0
0
1
2
0
0
0
0
0
0
0
0
0
0
15
7
10
4
20
0
10
0
15
0
0
0
0
0
0
16
6
12
34
13
A further polymorphism has also been found to occur in Tarachodes afzelii,
the common bark mantis. In this species occasional individuals are found with a
longitudinal black stripe running mid-dorsally from the pronotum to the tip of
the abdomen, and a second morph also occurs with two transverse black bars,
one on the pronotum, the other on the abdomen (Fig. 5). Between November
1970 and August 1973, 205 male Tarachodes were observed at Legon, but only
three were striped and one had a black bar (frequencies of 1.5 and 0.5%
respectively). Insects with a black stripe are better concealed to the human eye
DEFENSIVE BEHAVIOUR OF PRAYING MANTIDS
21
Figure 5 . Bark mimicry in mantids. Left: two female Turuchodes ufzelii one with black bars, the
other with a black stripe, on the body. Right: male Theopompella wesrwoodi with broad,
downwardly angled costal areas to the forewings. Based o n colour transparencies and mounted
specimens.
on deeply furrowed bark, but not on smooth uniformly grey bark. This is
particularly important in the last instars and in the adult female, but the adult
male has the abdomen covered by wings so that the black stripe is far less
conspicuous.
One adult female with a black stripe was captured. She had already been
mated, presumably by a typical male. Young from this female were reared to
the 3rd or 4th instar when stripes (if present) can be seen: 5 were striped, and 3
unstriped. One of the striped young was reared to adulthood and was a female.
She was mated with a typical unstriped male and of her young 6 were striped, 5
unstriped, and 4 had a line of black dots mid-dorsally. On the basis of such
meagre results it would be rash to suggest the genetic basis of the striped
condition, but I assume that it is controlled genetically and is not
an environmentally induced polymorphism.
Leaf mimicry
The defensive behaviour of two species of leaf mimics from Ghana have now
been described, Phyllocrania paradoxa and Panurgica compressicollis (Fig. 6 ) .
Both species resemble dead brown leaves. Phyllocrania is the more “perfect”
leaf mimic with the pronotum extended laterally and with frills on vertex,
abdomen and legs, but the legs are held away from the body so may be a visual
recognition feature for predators. Phyllocrania probably evolved from a typical
mantid (similar to Mantis or Sphodromantis in general shape) by developing
22
M . EDMUNDS
10 rnrn
Figure 6 . Leaf mimicry in mantids. Left: female Panurgica cumpresricullis; right: female
Phyllocrania paradoxa. Drawn from mounted specimens.
these frills and body extensions whilst retaining long legs. Sibylla represents an
intermediate stage in this sequence although its pronotum and body are too
elongated for it to be ancestral to Phyllocraniu. Panurgica on the other hand
has rather shorter legs and these are normally held very close to the body so
that they do not form a visual cue to predators. I t also has a very short body
compared with the enormous size of its head and forelegs. I t has evidently
evolved from a typical mantis by shortening and broadening the abdomen,
developing disruptive marks on the wings, and by adopting a posture with the
legs held close to the body. It is very closely related to the target mantids
Pseudocreobotra and Chlidonoptera which have a similar body shape and
resting position with the legs held close to the body (see below).
Bark mimicry
The defences of three genera that live on tree trunks in Ghana have now
been described, A morphoscelis, Tarachodes and Theopompella. All are
dorsoventrally flattened, but whereas Amorphoscelis is an active, running
mantid with only a general resemblance to moss or lichen covered bark, the other
two are less active species with highly cryptic resting postures. The middle and
hind legs are fairly long to give a good grip on vertical or overhanging branches,
but because of the low, flattened body they are held close above the substrate
and so are not conspicuous. The forelegs of both genera are held slightly
abducted in typical resting posture so as to smooth the contour of the insect
DEFENSIVE BEHAVIOUR O F PRAYING MANTIDS
23
when viewed from in front and to obscure any lateral shadow. In addition the
wings of female Tarachodes are greatly reduced in size whilst those of
Theopompella are disruptively coloured and are angled laterally (Fig. 5 ) . Thus
in neither of these insects do the wings form a conspicuous feature by which
predators might recognise the insect. One important difference between the
two genera is that whilst in Tarachodes the head is reflexed beneath the body
in the opisthognathous position, in Theopompella it is directed forwards in the
prognathous position. Neither position is suitable for actual feeding, but both
result in the line from the head to the substrate when viewed from the side
being smoothed and hence becoming less conspicuous.
Grass and stick mimicry
First of all it is necessary to distinguish two types of stick and grass mimics:
long legged insects with elongated bodies, and short legged insects with
(usually) short bodies. These two types have different morphological
adaptations and different resting positions. For convenience I shall refer to
them simply as long and short stick mimics and long and short grass mimics. I
shall consider long grass and stick mimics first.
The two habitats of long grass and the canopy of a tree or shrub both
contain many elongated structures, but whereas in long grass the stems are very
dense, in a tree the terminal branches are comparatively sparse. Hence in long
grass, provided an insect is elongated and of comparable body diameter to the
grass, it will be cryptic, but in a tree or shrub a more precise resemblance to a
stick is required to give a comparable level of protection. Thus it is that
long-legged grass mimics such as Oxyothespis and Leptocola have extremely
attenuated bodies, but they lack either a special resting posture or
morphological adaptations such as narrow head or notched forecoxae.
Compsothespis by contrast has a narrow head with the neck concealed in dorsal
view, so perhaps this rare, greyish species lives on shrubs rather than amongst
grass. Idolomorpha and Herniempusa have more cryptic resting postures with
narrow heads, pointed vertex and antennae, and forelegs held fully flexed close
beneath the pronotum, but they have broader and hence more conspicuous
wings and abdomens. Long stick mimics such as Danuria, Hoplocorypha and
Stenovutes have distinctive resting postures with numerous morphological
adaptations that increase their resemblance to sticks (details given in Edmunds,
1972). The grass-living Tenodera is of interest since it demonstrates one way in
which grass or stick mimicry may have evolved. Like typical Mantinae which
lack morphological resemblance to sticks or grass, Tenodera has a green-brown
polymorphism. But it also has a longer body and legs than do typical mantids,
and it rests in a stick mimicking posture with forelegs protracted in line with
the body. It has no other adaptations to stick mimicry (such as narrow head or
notched forecoxa), so it is thus intermediate in structure between typical
mantids and long stick mimics.
A study of the defensive behaviour of nymphs of certain mantids suggests
another way in which stick mimicry may have evolved. Balderrama &
Maldonado (1973) have found that late instars and adults of the large South
24
M. EDMUNDS
American mantid Stagmatoptera biocellata have a dramatic startle display
similar to that found in all large species of the Mantinae, but they found that
the early instars respond to a bird by protracting the forelegs and thus
increasing their resemblance to a stick. They found that as the insects
approached maturity so they responded less often by becoming stick-like but
more often by a display, and also that the further off the stimulus the more
likely they were to respond by becoming stick-like. I have found that the forest
mantid Cataspilota misana behaves in a similar way: from about the third instar
onwards (younger insects were not available) the brown mantids often adopted
a stick-like posture with the body lowered towards the substrate and the
forelegs extended in front of the head. This occurred occasionally in the adults
as well, though these also displayed. It should be stressed that this stick
mimicry is very imperfect since neither Cataspilota nor Stagmatoptera has any
of the adaptations to perfect the resemblance to a stick such as long body,
narrow head, notched forecoxae and projections posteriorly on the head.
Nymphs of Sphodromantis, Miomantis and Prohierodula have also been studied
but were never observed to adopt this stick-like posture. I t is possible that the
initial stage in the evolution of some stick mimics was simply adoption of a
stick-like posture; in other words that the behavioural adaptation preceded
elongation of the body and other morphological modifications.
The defensive adaptations of several short grass and stick mimics from Ghana
are now known, for example Paramorphoscelis, Galepsus, Pyrgomantis,
Catasigerpes, Anasigerpes and Chrysomantis. Pyrgomantis is obviously an
extremely specialized grass mimic. Since Galepsus is golden brown and has
what appear to be fire-induced melanics, this genus is probably also a grass
mimic. I have already pointed out that Galepsus has the structure and
behaviour that could evolve into either a bark mimic (e.g. Tarachodes) or a
grass mimic (e.g. Pyrgomantis) (Edmunds, 1972). The short stick mimics are of
two types, the amorphoscelid Paramorphoscelis, and the hymenopodid genera
Catasigerpes, Anasigerpes and Chrysomantis. These last three genera all conceal
the head by having it in the opisthognathous position; they have short and
hence inconspicuous legs with frills to break up their outline; and the wings (in
the male) are truncated posteriorly so that the body appears to arise directly
from the branch on which it is resting (Plate 1D). Paramorphoscelis is much
more similar in its structure and behaviour to Galepsus and Pyrgomantis. Its
legs are short and it rests close and parallel to the substrate, not angled away
from it, so that the insect appears to be a part of the twig on which it rests
rather than a branch arising from it. The head is held in the prognathous
position as in Theopompella and Danuria, but unlike either Pyrogomantis or
Catasigerpes. The prognathous position in a prostrate resting form probably
gives better concealment from lateral view than does the opisthognathous
position.
Finally Popa is an insect of very great interest since it has some of the
adaptations found in long stick mimics such as the closely related Danuria, but
it also has some adaptations of short stick mimics such as Catasigerpes (these
have been summarized above at the end of the section “Descriptions of
defensive behaviour”). It is thus in a morphological condition such that it could
evolve either into a long or into a short stick mimic.
DEFENSIVE BEHAVIOUR O F PRAYING MANTIDS
25
Reduction o f wings
In 1972 I pointed out that size of wings in the female is a compromise,
selection on the one hand favouring large wings for flight, and on the other
favouring reduced wings for improved camouflage. I t is important for the male
to be mobile since he must find a female, but it may not matter if he is
short-lived and dies soon after mating. Hence he has long wings. For the female,
however, it may be more important to be highly cryptic so that she can live
long and produce many oothecae. Some data which support this hypothesis are
given by Gillon & Roy (1968). At Lamto, Cbte d’Ivoire, eight species of mantid
in which females have reduced wings have sex ratios ranging from 16%to 33%
males, whilst two species in which both sexes are fully winged have sex ratios
of 43% (Mantis religiosa) and 39% (Statilia apicalis). The low percentage of
males in all species supports the hypothesis that females live longer than males,
but the very low percentage of males in species where the female is flightless
requires further consideration. Gillon and Roy also report on the stomach
contents of 11 black kites (Milvus migrans) and 1 grasshopper buzzard
(Butastur rufipennis). These birds had eaten a total of 44 adult mantids: 37
were of species fully winged in both sexes, 20 male and 17 female; whilst of
species in which the female has reduced wings 7 were male and none female.
These two sex ratios are significantly different (using Fisher’s exact test,
P = 0.032). The figures show that these birds were capturing a higher
proportion of females in species with fully winged females than in species with
flightless females. Since these two species of birds capture most of their food
on the ground, the explanation of the difference is probably that flightless
females are more cryptic and so less easy to find than are fully winged mantids.
This implies that the very low percentage of males in mantids with flightless
females is partly due to selective predation by birds.
I have now been able to examine females of eight species which have reduced
wings. Wings may be reduced in size so that they are useless for flight but still
important for display, or they may be completely lost. In Hoplocorypha and
Oxypilus the female is completely apterous and a startle display h.is never been
seen in either sex of these two genera. Consequently once the ancestors of
these genera had reduced the wings in the female till they could no longer be
used for flight, selection favoured their complete loss. In the remaining genera,
however, the wings have been reduced in size but not completely lost. In
Tarachodes and Danuria they are small but used during display. (They are
probably also used in display in Galepsus, since the male displays readily, but
no females were available for study.) In Pyrgomantis and Leptocola no display
was observed in the females but it probably does occur under some
circumstances. The single female Leptocola was damaged so could not be
properly studied, but each hind wing has what appears to be a large eyespot.
Possibly the wings are opened and closed rapidly when the insect is disturbed
thus giving a flash of two large eyes which may startle a predator into
withdrawing. In Miomantis paykullii and M . aurea the wings are only slightly
reduced from the size one finds in typical flying mantids of comparable size,
yet none of the females I examined was capable of flying. In both species the
females use the wings for display occasionally. Comparison with other species
26
M. EDMUNDS
of Miomantis indicates how wing reduction has evolved. In eight female
M. aurea from various localities in Ghana the wing length as a percentage of
abdomen length varies from 85% to loo%, average 91%. In thirteen
M. paykullii from Ghana it varies from 79% to 90% average 85%.Two females
of M. lamtoensis Gillon & Roy, 1968, have wings 44% and 48% of abdomen
length (one from the Mole Game Reserve, Ghana, the other measured from
Gillon and Roy’s plate of a female from Chte d’hoire). Finally M . bitumanensis
Roy, 1971, has wings of 6.5-8.3 mm length which I estimate to be about
35-40% of the abdomen length. In addition, wing length can vary in different
populations of the same species: thus M . misana (Giglio-Tos, 1911) from Loma
has wings that are 14-17 mm long whilst females from Nimba have wings
9-12 mm long (Roy, 1971). Presumably once female mantids ceased to fly
selection then favoured a progressive reduction in size of the wings, partly for
reasons of economy and partly because the insect can be better camouflaged
with smaller wings. Eventually a balance was reached in each species such that
the advantages of small wings for crypsis are balanced by the advantage of long
or conspicuous wings for startle display. I t is of interest that the species with
the smallest wings, M . bitumanensis, is the only one t o have evolved
conspicuous colouration: the anal region of the hind wing of the female is
tinged with red (Roy, 1971). Large wings in a startle display may intimidate
because they give the illusion of increased size, but small wings can also
intimidate if they are brightly coloured.
Defence against ants and ant mimicry
The commonest insect on every shrub and tree in tropical Africa is almost
certain to be an ant. Usually each individual plant is dominated by one or
(rarely) two species of ants, and these are typically very aggressive towards any
insect they encounter which does not belong to their own colony or is not one
of their associates (e.g. a scale insect or aphid) (Leston, 1972). If an ant tries to
climb on a mantid’s leg the mantid is most likely to fly or run away, or it may
kick the ant away so that it falls to the ground. Tarachodes lives on tree trunks
which are particularly densely covered with ants since the trunk provides the
only route from ground to canopy. It is not surprising therefore that
Tarachodes is adapted to living amongst ants. First, ants are probably its
principal food under natural conditions. From the third instar until adult, if a
Tarachodes sees an ant it immediately chases, seizes, and then eats it. The
hunting behaviour of Tarachodes with other insects such as grasshoppers is
quite different: it normally watches these and waits until they come near
before the final short rush and strike. This difference is probably adaptive since
ants have comparatively poor eyesight and are rarely aware of the running
mantis when chased, but larger insects such as grasshoppers or flies would see
the mantid coming and take evasive action.
Second, Tarachodes has a special defensive behaviour against ants. If a
mantid is satiated, or if an ant manages to crawl onto a leg without the mantid
noticing, then Tarachodes immediately strikes at the ant with the forelegs in
such a way that the ant is knocked off the substrate and falls to the ground.
Since Tarachodes nymphs are occasionally killed by ants in laboratory cages,
DEFENSIVE BEHAVIOUR O F PRAYING MANTIDS
27
and so presumably also in nature, this behaviour must be of considerable
importance.
Finally, Tarachodes females normally guard their oothecae until the young
hatch. Ene (1962) showed that this behaviour reduces the incidence of
parasitization of the eggs, but it must also prevent ants from finding and
destroying the ootheca. The young mantids are themselves ant mimics and they
scatter from the ootheca about an hour after emerging. In one of the four
oothecae which I observed at emergence the mother also moved away after an
hour. Three of the four mothers did not attack their own young, either
ignoring them even when they climbed over her head, or gently knocking them
away with her forelegs. One of these mothers struck at the ant Camponotus
acvapimensis several times, sometimes knocking it violently away, sometimes
capturing and eating it. A second Tarachodes behaved in a similar way towards
the ant Oecophylla longinoda, knocking all ants violently away, but not
harming her own young. One of the four Tarachodes, however, struck at and
ate two Camponotus acvapimensis, and she also struck at but then released her
own young. Next day her young were still nearby in her cage and she killed and
ate several of them. Evidently the parent can and does distinguish her own
young from ants, and for at least a few hours she has a strike inhibition against
her nymphs but not against ants.
Gillon & Roy (1968) show photographs of Galepsus toganus and
Pyrgomantis pallida resting on their oothecae, and they state that Pyrgomantis
feeds on Camponotus acvapimensis, one of the commonest grassland ants in
West Africa. It is likely, therefore, that these species have similar relationships
with ants as has Tarachodes afzelii.
The first three instars of many species of mantid are ant mimics. Since ants
are so abundant and are not often eaten by insectivorous birds, mimicry of ants
probably gives good protection to small mantids. In my earlier paper I
described the resemblance between first instars of Tarachodes afzelii to
Camponotus acvapimensis, Sphodromantis lineola to Oecophylla longinoda,
and Miomantis paykullii to Pheidole spp. Kumar (1973) has also described the
resemblance between Miomantis paykullii and Tetramorium sp., Polyspilota
aeruginosa and Pheidole spp., Phyllocrania paradoxa and Camponotus
acvapimensis, and Catasigerpes occidentalis and C. acvapimensis. To these can
now be added the following:
Miomantis aurea. The first three instars mimic Oecophylla longinoda. The first
instar is orange-red with black eyes and a black spot posteriorly on the thorax.
The second and third instars are similar but lack the black spot on the thorax.
The fourth instar is more reddish brown and less like Oecophylla, and the fifth
instar is mottled brown and is cryptic. Later instars may be either green or
brown.
B-ohierodula ornatipennis. Four small mantids, probably in the first instar,
were examined. They were similar in colour to the dark forest form of
Oecophylla longinoda with the head brownish cream; eyes pale grey; thorax
and forelegs black, but with a cream spot posteriorly on the thorax; abdomen
mottled red-brown and black above, black below; legs pale greyish yellow.
Later instars were green and cryptic.
Pseudocreobotra ocellata and Panurgica compressicollis. The first instars of
28
M. EDMUNDS
both of these species are shiny black and resemble Camponotus or
Crematogaster spp.
The closeness of the similarity between mantid and ant varies; thus mantids
resembling Oecophylla are very similar indeed. Some black mantids could be
said to resemble a variety of ants, for example Kumar (1973) and I give
different model species for Miomantis paykullii (see above) and the similarity
of Phyllocrania to an ant is not close since it has a pronounced vertex. The
following mantids do not have ant mimicking first instars:
Stenovates strachani. The young are elongated, like miniature editions of the
adult, but they rest in typical praying posture until the 4th instar when they
first start to rest with forelegs extended laterally as does the adult (Edmunds,
1972).
Tenodera superstitiosa. The young examined by myself and by Kumar (1973)
are elongate and do not resemble ants. This conflicts with the report of
Shelford (1903) to the effect that they are ant mimics.
Pseudoharpax virescens. The first instar is mottled brown, but becomes greener
in the second and third instars.
Chloroharpax modesta. The first instar is brown and is not an ant mimic.
Oxypilus hamatus. The first three instars have a dark brown head and
abdomen, buff pronotum and forelegs. They are contrastingly marked and do
not resemble any of the common ants at Legon, contrary to my 1972
statement. The young mantids referred to in that paper which were shiny black
must belong to another species, but unfortunately they were not reared to
maturity.
Thus in ten out of the fifteen species of mantid examined, the first instar
nymphs are ant mimics (summarized in Table 5 ) . These ten all belong to the
Mantidae or the Hymenopodidae. The five whose first instar nymphs do not
mimic ants (or at least not closely) belong to the Mantidae, Hymenopodidae
and Vatidae. In the case of Stenovates it is probable that the extreme
specialization of the later instars and adults as stick mimics renders ant mimicry
of the first instar impossible. There is a limit to the amount the body can
increase in length at each moult, and it is likely that the first instar must of
necessity be elongated in such exceptionally long mantids as Stenovates. Thus
it is unlikely that ant mimicry occurs in any very long species of mantid. The
record (above) that Tenodera nymphs do not resemble ants supports this
hypothesis since this mantid belongs to a family whose nymphs normally do
resemble ants, but Tenodera is a very elongate species.
Since so many mantids have ant-mimicking young one must suppose that
there is protective value in the resemblance, but I know of no evidence in the
literature to support this view. Further, one might expect selection to favour
any behavioural mechanism leading to a positive association between an
ant-mimicking mantid and the particular species of ant which it resembles. In
the case of Sphodromantis lineola at Legon I have searched carefully 3 3 1
shrubs and large herbs and scored each for presence or absence of Oecophylla
longinoda and for presence or absence of first instar Sphodromantis lineola
which mimic Oecophylla. The results, given in Table 6, indicate a positive
association between the mantids and Oecophylla. This association could arise
either through the female ovipositing amongst Oecophylla colonies rather than
elsewhere, or through the young dispersing mantids resting preferentially near
DEFENSIVE BEHAVIOUR OF PRAYING MANTIDS
29
Table 5 . Characteristics of nymphs of Ghanaian mantids
Family
Species
Subfamily
Amorphoscelidae
A morphoscelis
lagrecai
Mantidae
Tarachodinae
Tarachodes
afzelii
Mantinae
Cataspilota
misana
Prohierodula
ornatipennis
Polyspilo ta
aeniginosa
Tenodera
superstitiosa
Sphodroman tis
lineola
Mioman tis
aurea
Mioman tis
pay kullii
Ant
mimic
foreleg
display
+
+
-
+
+
+
+
Hymenopodinae Pseudoharpax
virescens
Chloroharpax
modes ta
Panurgica
c o mpressicollis
Pseudocreobotra
ocellata
Vatidae
boxing
display
+
Hymenopodidae Epaphroditinae Ph yllocrania
paradoxa
Acromantinae
tail
display
target
display
-
+
+
Oxypilus
hama tus
Ca tasigerpes
occiden talis
-
+
Stenova tes
strachani
-
Table 6. 3 3 1 plants at Legon scored for presence or absence of Sphodrornantis
lineola nymphs and Oecophylla longinoda workers
Oecophylla
Sphodroman tis
present
absent
Total
present
5
97
102
absent
1
228
229
Total
6
325
331
Fisher’s exact test (including the more extreme cases of 6:O and 96:229) gives P = 0.01 17
to Oecophylla, or through young mantids elsewhere suffering higher mortality
than do mantids close to Oecophylla. Since all six young which I found during
the survey were single individuals, they had evidently already dispersed; hence
their association with Oecophylla must be maintained either by the second or
30
M. EDMUNDS
the third of these mechanisms. I have no data on whether or not oothecae are
laid close t o Oecophylla colonies.
DISCUSSION OF SECONDARY DEFENCE
Function o f the startle display
Several points need to be added to my 1972 discussion of secondary defence
in mantids. First there are four possible functions to the display which I have
called a startle display:
1. For recognition o f a sex partner. I have observed mating in Miomantis
paykullii, Sphodromantis lineola, Tarachodes afzelii, and Oxypilus hamatus,
but I have never observed mantids to display prior to a copulation attempt
(Edmunds, 1972, 1976). Kumar (1973) also reports no display prior to mating
in Miomantis paykullii, Sphodromantis lineola, Tenodera superstitiosa and
Catasigerpes occidentalis. On one occasion a female Sphodromantis did display
to a male, but she was not in a condition to mate: although the male mounted
her, copulation did not occur for at least three days during which time she laid
an ootheca. Hence whilst it is possible that the display signifies to the male that
the female is not available for mating, there is no evidence that it forms a
normal part of courtship.
2. For demarcation o f territory. I t is possible that the startle display is often
given by conspecifics and that it results in one or both insects retreating. This
would result in spacing out and hence reduce the likelihood of cannibalism. I
have never observed a display occurring in adult mantids kept in the same or in
adjacent containers, but it does occur in nymphs of some species such as
Tarachodes afzelii. This is further discussed in the section on territoriality.
3. For luring prey to the mantid. Wickler (1968) illustrates the dramatic display
of the African Idolium diabolicum. This species has swollen, brightly coloured
forelegs which are reputed to act as a lure to insects which mistake the mantis
for a flower. However, Carpenter (1921) describes how an Idolium reared up
and displayed when it was approached by a monkey which backed away in
response t o the display. The related genera Idolomorpha and Hemiempusa also
have bright colours on the forelegs which are only exposed when they are
attacked, so it is clear that in Idolium too the posture is an anti-predator
display. In addition, I have found that it is almost impossible to induce a
displaying Sphodromantis to strike at a prey insect, and this indicates that it is
unlikely that the display of Idolium could ever evolve into a lure to attract
Prey *
4.As an anti-predator display. The display can usually be elicited by attacking
the mantid in a manner simulating attack by a predator. It can also be elicited
by presenting the mantid with a bird or with a model of a bird (Maldonado,
1970). Maldonado has also shown that the display of Stagmatoptera biocellata
does actually intimidate several species of birds, although the more persistent
troupials often succeeded in killing the mantid. In natural situations I have
observed a single Sphodromantis display when approached by a lizard
(Edmunds, 1972), and I have several times seen male Tarachodes afzelii trapped
in a spider's web display and slash at the approaching spider (Nephilengys
DEFENSIVE BEHAVIOUR OF PRAYING MANTIDS
31
cruentata). Hence it is reasonable to conclude that the display is directed
against predators, especially birds.
Following Maldonado (1970) the startle display of mantids, which appears
to be designed to frighten predators, can be called a deimatic response. Two
types of deimatic display can be distinguished: in Sphodromantis and
Polyspilota the display increases the apparent size of the insect, and in these
and other species the display is sustained and there may also be exposure of
bright colour marks, stridulation and periodic slashing at the stimulus source.
In female Danuria, however, the insect is so elongated and comparatively feeble
in appearance that raising the wings does not increase its apparent size to any
marked extent. In this case, the display simply involves sudden exposure of
bright colours which then vanish quickly so that the display is more in the
nature of a flash. Although I have not been able to examine a healthy
Leptocola, its wing pattern is such that I consider it probable that it too has a
startle display involving sudden opening and closing of the wings. Obviously the
importance of such a startle display involving a quick flash of colour or of
eyespots can only succeed if the insect then becomes cryptic again, and this
sort of display only occurs in species with elaborate primary defence.
Variation in the startle display
In my 1972 paper I drew attention to the variation in colour of spots on the
forelegs of Sphodromantis lineola .Further data are now available. Between
November 1967 and August 1973, 684 male mantids were examined at Legon.
18.5% have a black spot on the femur; 6.3%have red or blackish red spots on
the coxa instead of the usual yellow spots; and 15.2%have either more or less
than the usual eight spots on the two forecoxae. Since November 1970 I have
collected data on rainfall and also on population size, but there is no obvious
correlation between variation in the foreleg spots and either of these
parameters, nor could I detect any significant seasonal changes in frequency of
any of the morphs. Colour of foreleg markings also varies in Mantis and
Paramantis. Thus although all four Paramantis prusina that I have examined
from Ghana have red spots, elsewhere in its range the spots may be black or
white (Roy, 1965). Intrapopulation variation in spotting may prevent predators
from learning that a particular display pattern is a bluff, whilst interpopulation
variation may represent adaptations towards intimidating different species of
predators.
Evolution of ocelli
There are a pair of large ocelli on the forewings of Pseudocreobotra and
Chlidonoptera. These two genera are closely related to Panurgica on
morphological grounds. They all belong to the subfamily Hymenopodinae; they
have similar nymphs (ant-mimicking first instars, and with a “target” mark in
the later instars); and they have similar startle displays with the forelegs held
extended rather than flexed. Species of Chlidonoptera have rather less precise
ocelli than do Pseudocreobotra, and males have less circular markings than
females (Fig. 7) (Roy, 1964). But the problem remains of how the ocellus first
32
M. EDMUNDS
Figure 7. Ocelli in hymenopodid mantids. Left: female Chloroharpax modesra; centre: male and
female Chlidonoptera lestoni; right: male Pseudocreobotra ocellara. Green areas are stippled;
yellow and whitish areas are left white. In Chloroharpax the ocellus on the left forewing is
visible through the transparent greenish right forewing which lies above it. In the other three
mantids the ocellus on the lower wing is almost exactly overlaid by the ocellus of the upper
wing so it cannot be seen in the resting insect. Based on colour transparencies and mounted
specimens.
started to evolve. Many mantids have a small spot on the forewing. In
Chloroharpax this takes the form of a small black circle with a yellow centre
which perhaps resembles a leaf blemish or is a disruptive mark. The two spots
are also conspicuous during the startle display so selection could lead to a
gradual enlargement of the spots until a pair of ocelli formed. At the same
time, since one forewing is always visible in the resting insect, such a mark must
not be too conspicuous or else it might attract predators to the otherwise
cryptic insect. In the males of Chlidonoptera it appears that selection has led to
crypsis and active escape by flight (since they are lighter than the females)
rather than to perfection of the ocelli. But in the females, which cannot fly off
so quickly when disturbed, selection has led to more effective ocelli for
intimidation of predators even if this renders the primary defence less effective.
In Pseudocreobotra both sexes have equally perfect ocelli. I assume that these
ocelli intimidate predators during display, and that they are directed against
birds, but the only evidence to support this view is the work of Blest (1957) on
models with eyespots and on butterflies, using birds as predators. Similar large
ocelli on the forewings also occurred in the Carboniferous protorthopteran
insect Protodiamphipnoa (Carpenter, 1971). This insect also had raptorial
forelegs, but it apparently evolved quite independently from modern mantids.
Presumably the ocelli of this insect were directed against amphibians or reptiles
since there were no birds or mammals at that time.
TERRITORIALITY IN MANTIDS
Following MacKinnon’s description of territorial behaviour in the target
mantis Pseudocreobotra wahlbergi, I have investigated several other species of
DEFENSIVE BEHAVIOUR OF PRAYING MANTIDS
33
mantid to see if spacing out behaviour occurs in these as well. Four types of
territorial behaviour have been observed:
1. Target display. When nymphs of Pseudocreobotra ocellata and Panurgica
compressicollis see another nymph of the same or different species but of
similar size to themselves, they pump blood into the abdomen so that it swells
up, thus rendering visible a large circular “target” mark on the abdomen (Plate
2B). This mark in Panurgica is dark blue and yellow, and during display the
forelegs are either held extended laterally (as during a startle display) or boxed
in a way not unlike the boxing display of Oxypilus. This similarity in behaviour
between the two genera Panurgica and Pseudocreobotra suggests that they are
closely related (see section on evolution of ocelli). Evidence that this display
serves to space out individuals is given by MacKinnon (1970).
Figure 8. Tail display of nymph of Amorphoscelis lagrecai. The tip of the abdomen and the
cerci are moved alternately left and right as indicated by the arrows. Based on a colour
transparency and sketches from life.
2. Tail display. Nymphs of Amorphoscelis lagrecai have enormously elongated
anal cerci compared with adults or with other mantids. If two nymphs are
placed together they display by moving the tip of the abdomen in a circle so
that the cerci are conspicuously waved, rather like a semaphore signal, first to
one side then to the other (Fig. 8 ) . This is done particularly when about to
move and when coming to rest after having moved. Unfortunately these insects
are very difficult to rear away from their normal habitat (tree trunks in humid
3
34
M. EDMUNDS
forest) and it was not possible to study the behaviour further. Nevertheless it
seems likely that this display serves to inform other nymphs of the presence of
a mantis, and if this reduces cannibalism by spacing individuals out, it may
benefit the species.
3. Boxing display. Oxypilus, Catasigerpes, Anasigerpes and Chrysomantis all
give a boxing display, particularly in the presence of another insect of the same
species, and I have already (1972) given evidence suggesting that the display
serves to space out conspecific males. A possible boxing movement has also
been observed in one male Nilomantis, but further observations are required to
determine if it occurs regularly in this genus. In Oxypilus hamatus and
Catasigerpes occidentalis young nymphs also display to one another and usually
one of the two eventually retreats, thus indicating that the display results in
spacing out of individuals. Spacing out by means of boxing displays probably
occurs in all genera of the Acromantinae. In Oxypilus the colour of the forelegs
in the first three instars is quite different from that of later instars or of adults.
If there is a marked difference in size between two nymphs it is probably more
advantageous to the smaller one to retreat quickly rather than stay put, display,
and perhaps be captured and eaten. Hence if late instars have a different
pattern to early instars, this enables the small nymphs to recognise quickly that
an approaching mantis is not of comparable size to themselves, and to take
evasive action.
In Anasigerpes bifasciata there is widespread geographical variation in the
foreleg pattern (Roy, 1966), but it is not known if each population has a single
pattern, or if populations are polymorphic for this character.
4.Foreleg display, If two fourth instar nymphs of Tarachodes afzelii are placed
together in the same cage, they often display at one another. The display is
exactly like the adult startle display apart from the absence of wings: the head
and abdomen are raised from the substrate, and the forelegs are abducted, fully
flexed, thus displaying black and pale marks on their inner surfaces.
Occasionally the forelegs may be extended laterally for a second or two and
then flexed again. One or both insects may maintain a display for up t o five
minutes. Usually one of the nymphs then moves away and the remaining insect
eventually returns to a normal resting posture. Since the display is given
towards conspecifics, and since one usually retreats, I consider it probable that
the function of the display is to space out individuals, and so to reduce
cannibalism. The colour marks on the forelegs of all instars of this species are
illustrated by Gillon & Roy (1968). I have not observed males or females
display to conspecifics, so it appears that the display is confined to nymphs.
For several other species of mantid whose nymphs I have reared I have not
observed any behaviour which might possibly function t o space out individuals
(summarized in Table S), but obviously careful study involving several
individuals would be required to be certain that it does not occur.
In both Tarachodes and Pseudocreobotra the movements associated with
territorial display are similar to those used by adults giving an anti-predator
startle display. On the available evidence it is impossible to say which display
evolved first, but in both displays the mantis shows a reduced tendency to
make a predatory strike. It is perhaps surprising that there is so little evidence
of similar movements being used in courtship displays. If the displays I have
DEFENSIVE BEHAVIOUR OF PRAYING MANTIDS
35
described above do indeed space out individuals then presumably the colour
marks can be perceived by conspecifics. Yet although Oxypilus male and
female do box during courtship (Edmunds, 1976) I have never observed
Sphodromantis or any other large mantid displaying prior t o mating.
SUMMARY
The defensive behaviour of 18 species of mantids is described in this paper
and further details are given of the defences of 12 species whose behaviour was
described earlier (Edmunds, 1972). As a result the defences of 37 genera of
Ghanaian mantids are now known. Most species of the Mantinae lack a specific
resemblance to particular objects but have a greedbrown polymorphism, and
evidence is presented showing that there is a correlation between background
colour and colour of the mantid in Sphodromantis lineola and Miomantis
paykullii. Most other species of mantid have a highly specific resemblance to
bark, grass, sticks or leaves, and the evolution of these insects is discussed. Fire
melanism occurs in Galepsus toganus and Pyrgomantis pallida.
Evidence is presented which suggests that wing reduction in females results
in decreased predation by birds. Wing reduction gives better primary defence
but the wings cannot be completely lost if they are also used for a startle
display in secondary defence.
Many species of mantid have first instars which mimic ants and the fact that
S. lineola first instars have a positive association with the ant Oecophylla
indicates that ant mimicry is of defensive importance. Species which have
relatively unspecialized adults normally have ant-mimicking nymphs (e.g. most
of the Mantinae), but some species which have highly modified adults do not
have ant-mimicking nymphs, probably because already at the first instar the
nymph is “preadapted” t o becoming an adult and so cannot resemble an ant.
Tarachodes afzelii not only has ant-mimicking nymphs but also lives amongst
and feeds on ants. I t has a special technique for knocking off ants which come
near it and which it cannot eat.
The functions of startle displays and the evolution of ocelli in Pseudocreobotra are discussed.
Territorial displays which result in spacing out of nymphs are described.
These result in reduced cannibalism and they may also serve to partition out
the available food resources. Not all mantids have territorial displays, but four
different displays have evolved in different species which appear to have this
function.
ACKNOWLEDGEMENTS
I t is a pleasure to thank Dr P. Grubb, Dr R. Kumar, Dr D. Leston, Mr E. A.
Aryeetey, Mr J . H. Hynes, Mr D. Louis, Mr S. B. V. Mkhize and Mr S. Mensah
for providing me with specimens of mantids, especially forest ones, and for
their interest in my work. I am also grateful t o my wife, Janet, for discussion at
various stages of the work and for critically reading the manuscript, and to Dr
D. Leston, Dr D. R. Ragge and Dr R. Roy for help with identification of some
of the species. This work was prepared for publication during the tenure of an
Inter University Council Resettlement Fellowship at Exeter University.
36
M. EDMUNDS
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EDMUNDS, M., 1974. Defence in animals. A survey of anti-predator defences, 357 pp. Harlow: Longman.
EDMUNDS, M., 1976. Courtship, mating and possible sex pheromones in three species of praying
mantids. Entomologist’s rnon. Mag., in press.
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725-7.
GILLON, Y. & ROY, R., 1968. Les mantes d e Lamto et des savanes de CGte d’Ivoire. Bull. Inst. fond.
Afr. noire (Sir. A ) , 30: 1038-1151.
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KUMAR, R., 1973. The biology of some Ghanaian mantids (Insecta: Dictyoptera), Bull. Inst. f o n d . Afr.
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NOTE ADDED IN PROOF
Roy & Leston’s 1975 paper (referred to above) makes several changes of
name and of allocation to families, but it has appeared too late to modify this
paper. The main name changes relevant to this paper are as follows:
Amorphoscelis maculata becomes Maculatoscelis maculata; A. lagrecai becomes
Caudatoscelis lagrecai ; Galepsus toganus becomes Paragalepsus toganus ; and
Stenovates strachani becomes Heterochaeta strachani.
EXPLANATION O F PLATES
PLATE 1
A. Deimatic (startle) display of female Sphodromanth aurea.
B. Primary defence of t h e bark mimic, male Theopompella wesrwoodi.
C. Primary defence of female Chloroharpax modesta. Note the small eyespots which may
perhaps be disruptive.
Zool.
r. Linri. SOC.,58 (1976)
M. EDMUNDS
Plate 1
(Facing p . 36)
Zoo]. J . Linn. Soc., 58 (1976)
M. EDMUNDS
Plate 2
DEFENSIVE BEHAVIOUR O F PRAYING MANTIDS
D. Primary defence of the short stick mimic, male Cutusigerpes occidentulis. Note the position
of the body with the abruptly truncated wings touching the substrate.
PLATE 2
A. Primary defence of t h e leaf mimic, female Panurgicu compressicollis.
B. Final instar nymph of Panurgicu cornpressicollis showing the ‘target’ mark on the abdomen.
C.Primary defence of the stick mimic, male Popu undutu.
D. Resting position of female Chlidonopteru lestoni.
37