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168
TRAXSVAAL
AGRIC(;LTURAL
JOrRXAL.
THE ENTOMOLOGICAL SECTION.
- - - - - - - - - - - - ---- -
THE BAGHADA Bt'G.
(Bagmdc£ hila1'is.)
By 0. W.
HOWARD,
B.A., Assistant Entomologist.
EoI' some years it bas been very difficult to grow cabbages and
cauli:fiowel's in the Transvaal on account of the ravages of the Bagrada
Bug. It seems to be of universal distribution over this sub-continent,
and ha::; done a great deal of damage in Oape Oolony, R atal, and
Znlnland, as well as in the Transvaal In the Transvaal it is present
eYC'rywhere, being reported from pll:\ces of ever.)' elevation and
regions widely separated, like J~ouis Trichard, Barberton, Swaziland,
Rnstenburg, and Johannesburg.
One of our correspondents in
Barberton reported that a crop of cabbages was destroyed by this
insect, which cost £50 to plant. Another corr.espondent lost, recently,
a erop of cabbage worth £200, and many other reports tell of the
,loss of the entire crop. In Pietersburg anci vicinity it is necessary
-to illlport cabbages from, Johannesburg and Oape Oolony. In Oape
Colony the insect seems to have its ups and downs; some years being
very abundant and in others doing' little damage. ",\Ve have hoped
that such would be the case herEl, but for the past three years ther.e
has been no sign of any decrease.
The first mention of this inspct in Sout.h Africa is in the" Cape
Colouy Agricultural Journal" for .July 21, 18DS. In that article
]\11'. Lounsbury says that reports of its destructiveness had been
ltll1l101'ons <1nring t.he year, and came from widely separated regions.
He considered it, at that time, an insect iudigpnons to the country
bnt which rarely became a pest. In the report of the Natal
Entomologist 1003-4, :Mr. Fuller records it, not as an insect newly
introduced, but as one which had done cOIlsiderable damage during the
previollS pighteen months.
In the u.S.A. there is an insect belonging to the samB family
..as the Bagl'ada Bug, and closely resembling it in size and colour. This
· insect. is known as the Harlequin Oabbage Bug (.ilf1.£1·gantia
,hist1·ionica).
It began its work in the soutbern States, and has
· gradually spread northward until now it is found throughout the
· southern and eastern States, except in the extreme north-east. Its
food, like tllB Bagracia, consists of cabbage, cauliflowers, and other
cl'llc-iferous plants, and its other habits are very similar, but it is a
much easier insect to combat than the Bagrada Bug, owing' to the
fact that the winters in the part of the United States whBre it is
found are much more severe than in the Transvaal, which compels
it to remain concealed in some protected place during that season, ::Ind
,-makes its trapping in the spring. an easier matter.
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.10l·HXAL.
160
Olassification.-The Bagrada Bug belongs to the order of insects
kllmnl as liemiptera, the True Bugs. In some parts, all insects are
known as bugs, but technically this is the only group which can
receiye that name. :Furthel', it is a member of the family
Peniaiomidm, one of the sub-divisions of this order. :i\iembers of the
family PentatomidaJ, or Stink Bugs, are very abundant in South
Africa, and can be easily distinguished by their flattened appearance,
triangular shape, and the foul odour which lUo~t of them emit when
handled roughly.
The technical name for the Bagrada Bug,
according to the South ~\f]'ican J\Iuseum at Capetown, is Bagrada
hilaris. In the absence of any previolls common name, ::\£1'.
Lmnsbury, Cape Government Entomologist, christened it Bagrada
Bug in 1898 .
•\11 the members of the order JIemiptem obtain their food by
'Sllcking. If a Bagrada 0]' an:" other bug be examined, there will be
found on the lower side of the head a long, jointed tube carefull:
folded back between the leg,; aloug the lower side of the body.
This ttl he contains seyeral shall) bristles, and when the insect wishes
to eat, the tube is brought forward, inserted into the plant tissues,
anel the juices sucked up through it. This method of feeding makes
them a much more difficult group of insects to combat than the
,chewing insects, for they are perfectly immul1<: to any stomach
poison which might be sprayed on the plant.
Tis 11'or7c.-Considering the method mentioned above, by which
iheBagrada ]3ug eats, one would not expect to find the results of
its work v,ery evident. But such is not the case; it can be detected
:at once. It sucks the juices from the leaves of the cabbage or other
plants so rapidly, and in such quantities that nothing but the tissue is
left, anel the leaves soon shrivel np and dry, making the plant look as
-if it lJad been scaldecl with boiling water 01' burned. Young plants
'soon succumb entirely and dry up, while older plants are seriousl,v
hindercd.
Food Planis.-The food of the Bagrada is mostly COllfinell to
,cruciferous plants (the Mustard Family) among which cabbage, cauliflower, kohl-rabi, turnips and radishes suffer the most. But it is also
fond of lllustard, wall-flowers, stocks, canuy tuft. and alysseum, and
.often attacks nasturtiums, which belollg to the famil.Y Gemn'iacaJ, and
.has even been reported as injUl'ing mea lies, wheat, and holyllOcks.
A few were found on Cape gooseberries at Pretoria last year, and
·oviposited on the plants, but they seemed to find it uncongenial and
,soon left.
In our experiences at Pretoria, we have found that it prefers
mustard first of all, next to this radishes, turnips and nasturtiums.
Eycn when cabbages were in the plot next to these plants they wel'e
not tone bed until the mustard and nasturtiums were all finished. So
,eager are they for mustard that, when numerous, they will scareel~·
;allow it to acquire its third leaves unless it is pl'otected by a netting.
Description and Life H isiory.-The adult Bag-rada is a small,
:flat insect from 4 to 'I llun. (.16 to ,28 in.) long, the male being' only
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TRANSVAAL
AGRICULTURAL
JOURNAI••
about two-thirds as large as the female. They are triangular il1'
general outline. The broad end in fron t is formed by a narrow,.
almost rectangular plate, in front of which projects the small hend;
backward from the plate extends a large triangular shield, on each
side of which are the wings. The upper pair of wings are thickened
and stiff at their bases, and so arranged that the thin membl'aneous
tips overlap each other. The general colonr is black, bnt thcre are·
nmnerous symmetrically arranged orang'e and yellow streaks and spots.
on both npper and lower surfaces. In fact, the lower surface is nearly
all yellow in most specimens. The eggs are small, barrel-shaped
affairs, a bout i 111111. long by -t mIll. wide, rounded on the lower surface,.
but rather flattened on top, with a groove running around thc edge,
forming a lid. Along this line the egg breaks when the yonng insect
hatches. The Sl}rface of the egg is smooth and glossy, at first a
creamy white, but gradnally bccominp: a deep orange in COlOlll' as it
neal'S the time of hatching.
~l'lle eggs ai'e deposited, singly or in
gronps of three or four, but arc: neve]' sct in regular rows, side by side,
HS with most insects of this familv.
Sometimes thev stand on end
supported by leaf hairs, or often o~ theil' sides. The" mother lli'nally
places them on the uuder side of leaves or ahollt the 11ases of leaf
stalks, where they are protected, and seldom 011 the npper snriace.
The Bagrada passes through an incomplete metamorphosis, that
is, the young insect which hatches from the egg resembles tIl(' adult
insect in general appearance and assumes the adult form by a series;
of moults, and not by a resting stagc as with butterflies and moths.
The young Bagrada just hatched is abont 1 mm. (.4 in.) in length, and
resembles the adlllt in shape, except that it is not quite so flat, and
possessess no wings. The head and thorax are black, and the abdomen
of a deep orang.e colour with a row of black spots down the ccntre,.
lllld another of black triangles all around the edge.
At each moult,
these black-spots become larger and larger until at the last stage, just
before the adult, there are only a few reddish spots left on the
abdomen. These immature forms, or nymphs, as they arc called,
1l10nltfive times.. prodncin~ the adult insect at the last moult. \Yith
each moult the wing pads, black, triangnlar projections! from the
llind edge of the thorax, become larger and larger, until fin11l].' the
fnll-sized wings are produced.
The number of generations in a year has not yet. been determined.
Dl11'ing the snmmer the adults began to lay eggs in 8 or !) days
after copulation. In 9 to 13 days the eggs hatched, ,,-hile the
nymphal stage lasted from 35 to 40 days. In the low wId they
seem to be more active during wint.er, and may bt'eed throughout the
year. In the high veld the c1evolopmcnt seems to be retarded in the·
winter; at least, about Pretoria the insects hide under rubbish and in
cracks in the soil during cold periods, only coming out when i.t is.
warm, It has been impossible tf) obtain any eggs at PrE'iOl'ia this.
winter, or to make nymphs complete their development, nntil the
latter part of the winter when it begaD to get warm. In Oal)c Colony
t he bug is said to breed throughout the winter, but its development is
retarded somewhat, and it is not. (lestrnctive at thilt season.
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'I'RAX~VAAL
AGRll'l-L'JTRAL
JOUr.NAL.
171'
Pj-e'vrmtion.-Xo natural enemies of the bug have been found ilL
the 'J'l'ansvaal, bnt the fact that it is abnndant some seasons in the
Cape Colony, and not others, seems to point to the work of some·
parasite in that country, and we are at present negotiating with otherentomologists for the importation of such parasites, whenever pOf'f'ible.
All remedial remedies mnst be in the natnre of prevention rather than
direct destruction.
Owing to the method by which the inseet pats,_
sprays whieh act as stolllach poisons, such as Paris green, or arsenite
of soda arc useless; some contact insecticide, such as resin wat:h, must
he ell1ployell when spraying is feasible.
Clean culture amI cleanliness about a farm are two essential
points in its suppression. The Bagrada must have shelter to protect
it (l1ll'illg the cold spells of winter, henc(' if all rubbi~h is removed
from the fi('lrl" there i'l no plac? for it to hi(I(1. All re:II~lins of crop::;,.
i:Hwh as cal)bagu alltl caulifiower stumps left in the field oyer winter,.
£111'1116h it llourislnllent, as do all remains of stocks, wall-flowers,
nasturtiums, or other favourite food plants. Hence all such plants
shoul d be pu Hed up and burned, or destroyed ill other ways, as soon as·
they are finished with. An weeds belonging to the mustard family
should be de:;troyecl, and not allowed to grow on the farm. Such
c1'l1cif<'1'011S weeds growing in the Transvaal are the following, some'
of which are natives, while others have been introduced from other'
countries : Nati'l:es.
Bmssica stj'igosa, Dc., Klippan, Boschvelcl.
]31'(1ssica st1'igosa glabrata, Mooi Hiver, Kal'ieboseb.
Oal'damine africana, Linn., ,\1o.,7oorlllllsh, Barberton.
Jfl'liophila }JUs'illa, L., '\Voodbush.
"
rigid'il.lscula, Sond., Bal'brrton.
"
sp., Johannesburg.
Nasturtium i1uliC11:rn 1:ntegrifoZiwn, Dc., Pretoria.
11l-iens.
Ba.rba.rea Pj';ccox, H. Br., Pretoria.
Brassica r;a.mpestris, L. ("Vild nape), Stalluertoll.
"
nigra., KoCh. (Black Mustard), Standerton.
Oapsella bU1'sa-pasto1'is, ~lamch (Shepherd's Purse), Belfast,..
Johannes burg, Pretoria.
OO1'onopus didymus (L.) Smith ('\10.,7 art Cress), Pretoria.
Lepidium capense, Thunb. (Cape Pepper-Cress), Pretoria aud'
Belfast.
N asturtiu1n officinale, R. Br. (Water-Cress), Aapjies River; near
Standerton, Johannesburg.
R'aphanus mphanistrum, Linn. (Jointed Charlock), Potchefstroom, Belfast.
S'is!)mbl"ium capense, Thunb. (Cape Uustard), Standerton.
E1'uca sativa, PretoTia.
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TRANSVAAL
AGRICULTURAL
JOUHNAL.
The above list was compiled by the Government Botanist, :Mr.
J. Burtt-Davy, and further information regarding them may be
-obtained from a paper by him entitled, " Alien Plants Spontaneous in
·.the Transvaal," and published in the Report of the South l"dricnn
Association for the Advancement of Science for 1904.
If a crop is destroyed or hopelessly damaged by the insect, have
.it removed at once, thereby destroying most of the bugs on it. Never
plant cruciferous crops which grow at different seasons near each
-other, otherwise the insects will pass readily from one crop to the other
and destroy both.
And always rotate the crops if possible; that
cis, plant the cabbages in a new place each year, removed as far as
.possible from the plot utilized the former year, and plant some crop
·of an entirely different character on the old plot.
(heat results can be obtained in the way of clearing the ground
·of the bugs before planting. This can be done by putting out piles
·of olel rubbish in the field where the plants are to be set.
The
insects will collect in these, and they can be destroyed.
A 11111Ch
better scheme is to place leaves of old cabbage; or even such plants
.as eastor oil, on the ground. The bugs assemble under them on cold
nights, and a boy can go about early in the morning and shake thelll
int·o a tin upon which a little paraffin has been pOUl·ed.
That the bugs are so fond of mustard is very fortunate. 11
'Small plot can be planted in the field to be used for cabbage or
eauliflower later. This should be protected by a covering', whicl) can
be easilv made' of a frame-work of a few stakes and wire with butter
cloth st~'etched over it. Such a coverin.g for a plot eight feet square
need t~lke only 13 yards of butter cloth, at a cost of 3a. 3d. The
-edges of the cloth should be held down firmly with em·th. After the
mustmd is fully grown the covering can be removed, and the bugs
,,-ill gather upon it in great numbers. Then it should bc destroyed,
and with it the bugs, by burning or spraying thoroughly with pure
paraflin. In some cases it might prove easier to grow the mustard
in tins in the house, and remove it to the fields when needed, destroying
it in the same manner after the bugs have gathered upon it.
After the ground has been thoroughly cleansed of bugs' in the
above ways, the cabbage can be planted, and will be un attacked until
large enough to resist. If, howeve, the bugs are present in unusual
numbers, rows of mustard might be planted again betw.een the rows
.of cabbage, and destroyed after the bugs have gatheTecl on them and
the plants have become large.
Instead of the above method, very good success has also been
,obtained by netting the cabbage until ~vell grown. This is done by
inserting a small stick beside the plant and stretching over it a small
sqnare of hutter-cloth, pressing down the sides of the cloth firmly with
soil. Old tins have been tried but proved useless, as they did not let
~n enough light and ail' to the plant.
'VVhen the plant becomes larger the bugs have . often been kept
jn check by the use of resin wash, or castor oil lemulsion. Other
,contact insecticides such as paraffin emulsion would be equally
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j'llIlf
('XXX!i.
The Pigweed Caterpillar en/J'ild";1I1I I:... ifl'"')'
;'-.:. ...
Fi'-':",
1. - · l\~' \\ · (·v(l
( . IIIIIU'fIJlII,"",; /Jff/li""!I/!IIS)
~. - (.~al('l'pilb]'"
Fi.~, :-( - -(·at~l'ld!l:l~
..
Vi!.!. ·I. - ·('atc)'l.ill:ll'''
I
ill IJi.~\,·('{'d:
Id}:L
I;. - .\dLlIT II'"li,:
I)y c:;\fl'I'1Ii 11:lr:-:.
(·("·~nll k:1r \\'ll~ ( 'Jl 111('," II:l\" l' C:ltCI1: 11~ltll)":L1 ",izL'.
Il)l:l tl li':l"c.'tt
Fi~· . ,J, - - C·:lf, ·l'i1i i i;l l' . . \\"1 ,',,' , d", ·- . ('\
y,~·.
V;l('ll
n:1!lIl',')1 -.:iZI'.
ll;ltLlI';i1
It-;)!'.
,;ze.
:1 l.:H 'l{" j :: d
d :"'t ':l -' . I
H '
.:11
"':/1 ',
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®
®
/'/11 1,. ('r .Lfl II .
Th~ Bagrad ,~
l-'i:_. I
">..:'. ,: '
til l
In...;"
t l i'
Bug (/I"!l rlll/' 1 " dlll';",,-
la dl"' !, h ,. d·. .. I I · 111 (i)f\"l'rl('d) .
Fi ., . :!.
I-' i·_ , :L
,.>.! :.! " 1111
I"i ·' . .'"'.
,,' i ~. ~).
.\dllll
1111~'~ : 'J~:d,'
.\ .Iull
hl l ! "':
IIlId, ' r ~Id ,' HI l,olil -r:tI,i
I-: ~" , : "n':!1
1,,;11 ;
JI. l l l l l;t! .. iZ t"
t·ld;lr~'·1 1.
ii' ("'/:'1'" ,,<1
I l tlilillt' cI 1':1 \\' il1 : (If C '~ 1.!. "'~1I 1 \\' ill !! l ilt' ;,1.
I" j" I
y ,tlllI ~ "'1; 1 ~~ '~ III 11 ,"1111, 11 :-; .1 1' lilt' I b!..'I'ati:l · \'111 I l' ':.!' I '1I.
I,' ic:" :" I; :lt ld 7.
tIll
It,r,
It:t ll in tl "1 :/.1..',
:lllfl
f"111:i1 e 1111
n'~111
,
t·l da J'.~·(·d 'l~.
I h ill''':,
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The Bagrada Bug (/l,'!/)',,,!,, 1,;1,/1';"').
i...,:·. I. - \11I ...;I:Hd J...,;I4",1 IJ' 1~;!~J';HI;l HII'!"',
I '.! .~. ;\11! ...;larcl ~Tn\\'11 1;1 1«1CI' ,I {"I\""]'~,j tl l:!t \ i]j''';'''; (' oIlI d 11 ,,1 r '_:\I,11 : 1.
I.'i." . :1. ("1\"('1' U":i'il t. , 1')'id"'I'! f 11 (' all l l\" " ,d,,1 11\' Jl lu ..:f;tl'll.
I.' ie'. I. \a"':II I I'lillll l .. l,ill,',1 \,,' g:l '.!r:lll:l I: I I~.. .
i' 'i~. ;'. ~ T ill': ;111.1 11' ,1 . . I! ....\ , j II : \,I"q le 'I'1 i :aIJh l ~ I ' ldallt . . fJ" 'Jf t !j l' l'll..! ~ . The I ill"'"
;In' Jill!
;t ....
~ , ,(,d ;l:-. (t)I' I H ~ :'... ,
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Tl(A~"VAAL
AGHICULTURAL
JOURXAL ..
173
effective, but resin washes are the only ones which will stick well to
the glossy lcaves of the cabbage and cauliflower. The wash should
1)e applied very thoroughly, and every Rart gf the plant should be
covered, in order that all the bugs may be reached, for it is only b'y
contact with the spray that the insect is killed.
A valuable auxiliary in clearing a field of the bugs is a few fowls,
providing that they do not take to eating and scratching up the plants.
The fowls can be allowed to roam OV8r the field, and in winter, when
:few insects are a bout, will greedily devour the bugs. In a small
garden, where only a few flowering plants, or half a dozen cabbages,
are trOll bled with the insects, hand picking is sufficient. The hugs.
can be shaken into a tin of watel' and paraffin, and tlms destro~·ed.
~
* * *
THE PIGWEED CA'"J'ERPILLAR.
By O.
'V.
(Camdrina exigua.)
B.A., Assistant Entomologist.
HOWARD,
During the past summer an insect appeared in the Tran~vaal,
which, as a pest, was quite unknown before in South Africa, although
its presence here was noted some years ago. . The orchard connected
",ith the Entomological Laboratory at Pretoria had become covered
with « pigweed,". 01' "1l1'ist·brede" (Amamnthus paniculatus), und
early in J annary this pigweed was found to be badly eaten b~r small
caterpillars. A little later, this caterpillar was found to be destroying
to bacco, cotton, mealies, and many other plants in different parts of
the Transvaal. For lack of a common name for the insect in Ronth
A.frica, and because it was first found in such abundance on the
pigweed, we have called it the" Pigweed Oaterpillar."
a, moth; c, larva, lateral view; c, larva, dors~l ,,·lew,;,
d, bead of laJ'va ; e, egg, viewed from above;
egg, from side-all
enlarged. (From Bul. 57, U.S.A. Bureau of Entomology.)
CaJ'II.drilllt p.d,qult.'
~
.t;
])csc!'iplion and Life History.-These caterpillars were fl'OlU
inch to Ii 'inches in length, of a slaty grey colour, with a lighter line.
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TRANSVAAL
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:.passing down the back, and a darker one on each side just above the
-spiracles, while below them was a yellowish band. The under parts
were greenish, the head brown, and the shield on the dorsum of the
first thoracic segment bore three whitish longitudinal stripes. There
-were several variations in colour, from very light dirty yellow, to
.almost black or brownish individuals.
Sev61'al of these larvffi wel'e taken into the laboratory and placed
_in a breeding cage on January 10th. They pupated on the 11th, and
.adults emerged on the 22nd. Another lot brought in on the 18th
:pupated on the 20th, and adults emerged on .February 1st. Still
another lot pupated on January 23rd, and adults began to emerge on
February 2nd. Thus the pupa stage varied from two to eleven days.
Eggs were not obtained, so the length of the larval stage could not
be determined. The pupa is brown, with the abdomen very dark,
but the head and wings have a y-eenish tinge. It is about i inch
.in length, and has at the caHdal extremity two long slender spines.
A case is made in the soil where the larva transforms to the pupa.
The adult moth is a small, light grey, inconspicuous creature,
which flies only at night, remaining concealed in grass and weeds during
·the day. The wing expanse is about lt inches, or somewhat less. On
the front wings, just before the centre and near the front margin, is a
. small, round, pale ochreous spot, and just beyond it, toward the tip of
the wing, is a large, prominent, r.eniform spot, with ochreous or darker
·centre. Along the outer margin is a series of very small black spots.
The hind wings are semi-hyaline, and of an opalescent ,,,,hite colour,
with the veins and outer margin tinged with brown. The abdomen
is dark brown, with a tuft of brownish hairs at the tip.
The number of generations of this insect in a season has not yet
been determined. A single specimen was reared from a larva
fOlUld on beets, towards the end of N oyember last. The adults of
-this generation probably laid the eggs for the larVffi which appeared in
January.
No other larvffi were found during the summer about
Pretoria, but larvffi were reported in the middle of February, and again
in the last of February, so that probably three generations occur in
_a season.
Food PZants.-Only a few days after these caterpillars were
discovered on the pigweed at Pretoria, reports came that they were
. doing a great deal of damage in the Waterberg District to tobacco,
. cotton and mealies. Upon investigation it was found that they were
also eating several wild plants, among which were Oxygonum SI).,
Limeum visco sum, and CZeome monophylla, val'. cordata. An immense
amount of damage was done to a tobacco plantation in that district.
N ear Pretoria, they were found eating young eucalyptus trees, grape
vines and garden beets; from Piet Retief they were reported as
feeding upon potato vines. The pigweed (Amamnthus panic1tiai1),s)
seems to be its favourite wild food plant, probably because of its
:abundance, fo1' it is the most abundant weed in the Transvaal, being
especially common in neglected gardens, around cattle kraals ancl
-manure heaps. It is a -native of tropical America, and has been
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TRAXi'\'AAL
AGlUCCLTCRAL
JOURXAL.
17;:;
introduced from tllere to lllany parts of the world. In India it is
,cnltivated for the seed, which is used as food.
11 istorical.-The history of this insect is of considerable interest.
It is of almost universal distribntion over the world, but seems to
lwve originated somewher.e in the Orient. Just where, I cannot say,
,o"'ing to lack of literature. From there it seems to have spread
\YC'st"'ard throughout Europe, sout[nvard into Africa, and eastward
into .;\sia. IIampsoll mentions it in his "Fauna of British India,"
:\10th:3, vol. II., and again from Hawaii, in his "Fauna Hawaiiensis."
Vl'om there it spread to the western coast of America, anel is gradually
advancing eastward over the American continent.
The progress has
been very slow; bnt at pr,C'scnt it is known in middle and southern
Europe, England, Mauritius, :Madeira, Canary Islands, Afl'iea, Asia
J\iinor, China (?), Japan, Inclia, Australia, Hawaiian Islands and
r.S.A. west of the "Jiississippi \Talley, although spreading eastward.
It seems to be unable to sUl'viyC' v.er.'· sev('l'C' colfl, so is founcl mostl."
in tllOse countries which have mild winters.
In 1889 it appeared iu Colorado, U.S.A., as a very great pest of
sugar beets. 1\lany hundr.eds of acres of beets were eompletel.'"
.defoliated, and even the roots t hemselyes partly devoured. For this
reason, in the United States of America it is known as the "Beet
Army-worm." In that region it was found that the moths laid their
eggs from fiye to sixteeen days after emergence, each female depositing
about 350 eggs, which were placed in groups of twelve to fifty on the
undersides of the leaves, each mass being coated with a down."
secretion. In about four or five days the eggs hatched; larvffi
were full grown and pupated in about 60 days.
The pupa stage
lasted 14 to 16 days. There were three generations, and the moths
of the last one hibernated over winter. In Texas, where it appeared
later as a pest on cotton, the life history more nearly approached what
we found it to be in the Transvaal last summer; eggs hatched in
three days; the larval period lasted 23 days, and the pupa stage about
seven days; the complete life cycle was passed in about 40 days.
The insect has been carefully studied in the L'"nited States, both
as a serious pest of sugar beets in Colorado, and a slight pest of
cotton in Texas. Besides these host plants, it has been found upon
potato vines, pears, apple trees, table beets, onions, maize, mallow
(J[alva borealis), lambs' quarters (Ohenopodium album), pigweed
(.lmamnthus retrofiexus) , Nicotiana glauca, saltbush (A triplex), wild
snnflower (Oleome sp.), plantain, all plants closel," relatecl to beets,
'and many wild weeds and grasses.
Like all the other army worms,
to which it is closely related, it is liable to attack any form of
vegetation, although it has ne\'e1' been krown to move in masses from
"one field to another, as is the habit of most army worms.
I was interest~d in comparing the above iist of plants with the
flora of the Trans\"aal, and found, with the assistance of the
"Government Botanist, the following plants occurring here,. either
native, introduced, or cultivatetl, which are closely related to, or the
.same, as those in the above list :-Amamnthus paniculatus,
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176
TRANSVAAL
AGRICUL'ft:RAL
JOURXAL.
Amamnthus spinosus, Ama1'anthus thunbergii (native in South Africa):Chenopodium album, J.lfc£tv(£ pa1'vifio1'a, Nicotiana glauCct, PlaHwgo>
major, Plantago l(£nceolatc~, Oteome monophylla cordata, wild grasses~.
and the following cultivated plants :-Mangels, beets, onions, potatoes,.
peas, ap])les, mea lies, and salt bush (Atriplex sp.). Those upon which.
I have found the larvre have been already mentioned. It will be·
interesting to find whether the remainder also are host plants iu this.
country.
In spite of the universal presence of this insect, it has occlU'l'edl
hl sufficient riumbers to be a sl3rio1£s pest only in Oolorado in 1Rv9,..
and this past season in the Transvaal, while it has been present as a
pest of cotton to only a slight extent for several years in the F.S.A ..
Our observations upon the insect last season seemed to indicate that
in the Transvaal it will prove a pest during the dry seasom. It is'
always the small and stllllted plants which suffer the most, and, in a wet
summer, they would grow so vigorously as to successfully resist the'
attacks of the caterpillar without any artificial intervention.
Remedies.-Natural enemies seem to be very abundant. Large·
numbers of Tachina flies were bred from the larvre, and a bacterial
disease appeared about Pretoria, which carried off fully three-fourths.
of the larvre. In tobacco fields where fowls were allolVefl to wander'
about, they almost exterminated the caterpillars.
In the way of artificial remedies, Paris Green was found very
efficient. This can be applied to the affected plants either dlT or'
mixed with water in a spray. To apply dry, the Paris Green ;;honld be
mixed with flonr or air-slaked lime, in the proportions of one pound'
of Paris Green to ten or twenty pounds of the lime or flour. The'
lime should be carefully sifted through a fine sieve bef01'e mixing, to·
insure its not being coarser than the Paris Green. The application.
can be made by placing the mixture in a coarse canvas bag, and
sending a boy with one of these in each hand, 01' suspended fl'om H
rod over his shoulder, up and down the rows of tobacco or cotton. A
slight jar will cause the contents to sift through the bag and over
the plants. By using the two bags two rows of plants can be clonc at
one time, and thus hasten the work. If the spray is pl·eferred, i.t
should be made by mixing one pound of Paris Green in each 200
gallons of watei'. To this must be added at least two pounel,; ot
freshly-slaked stone lime. If too little, no lime, or air-slaked lime is.
added, burning of the foliage might be the result. This !'olntion
should be applied with a spray pnmp, in a fine spray, Sl} as to con'l' am
parts of the plant with the solution.
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