Mariposa buho (Spanish)
Caligo spp.
Class:
Insecta
Order:
Lepidoptera
Family: Nymphalidae
Subfamily: Brassolinae
Genus: Caligo
Distribution
Mexico to the Amazon
Basin
Habitat
Primary and secondary
rainforests. Common
around banana plantations.
Food
Caterpillars feed on plants
in the banana family such as
heliconia, plantain and
bananas. Adults act as
pollinators for the plants
they feed on.
Reproduction
Owl butterflies engage in
lekking. Eggs are laid in
small batches and hatch in
about twelve days.
There are roughly 20 different species of owl butterfly, so
named for the large spots on the undersides of their wings that
resemble owl eyes when the wings are open. They are the
largest butterflies in Costa Rica where they are widespread and
common up to an elevation of 1,600 m.
They are often observed flying at dawn and dusk or perched
along roadsides and edge habitats during this time. Their
numbers increase during June and July when the rainy season
arrives on the Pacific side.
Larvae have voracious appetites for the leaves of the banana
plant, a non-native species which has been readily accepted
because of its close relationship to heliconia. They are
considered pests in banana producing countries. Feeding usually
takes place at night, and they will line up on the underside of a
leaf’s centre vein during daylight hours. Adults feed mainly on
rotting fruit.
During the mating season, males assemble along roadsides and
edge habitat at dawn and dusk to competitively engage other
males in aerial encounters and display to attract females. This
practice of gathering in a traditional place to mate is known as
lekking. These displays often last for about 30 minutes, during
which time the males shiver in order to elevate their thoracic
temperature in preparation for mating. Males have androconial
tufts on their hind wings and the sides of their abdomens. These
organs produce pheremones which are released during
courtship. The pheremones give many species a characteristic
odour. The males of some species often smell strongly of
vanilla.
Development
Caterpillars grow to a
length of 12 to 15 cm.
The head of the caterpillar is spiked like a Triceratops. A gland
on its prothorax everts to secrete noxious chemicals if the
caterpillar is attacked. It pupates while hanging head first from a
silken pad. The pupa usually hatches in about 21 days. Adult
butterflies can live for many months.
Characteristics
Adults escape the heat of
the day perched upon tree
trunks in the forest shade.
Wingspans reach 15 cm.
They are crepuscular, which means they are most active at dusk
and dawn. Few avian predators bother them at these times,
which is to their benefit as they only fly a few metres at a stretch
and birds would have little difficulty following them. The
insides of their wings feature assorted iridescent color
combinations which vary from species to species and may aid in
the avoidance of hybridization.
Adaptations
As its name implies, it looks
very much like the head of
an owl when its wings are
spread. When at rest, its
wings are closed and other
animals do not see the “owl
face.” To them it looks
more like the head of a
mammal or a large lizard.
Eye-spots may act as ‘false eyes’ to startle or disorient predators
and to divert attacks away from the vulnerable abdomen of this
very palatable butterfly. Individuals are often seen with wing
damage in the area of the eye-spots, suggesting that these
markings do indeed attract predator attention. They are active
mainly at dawn and dusk, where their main predators appear to
be small lizards like Anolis. One theory states that the ocelli
resemble the head of a large Hyla tree frog, which preys on
Anolis. Adults have sturdy probosces for piercing the skin of
fruits.
Status/ Threats
Much of their forest habitat
has been destroyed and the
banana plantations they
frequent are sprayed heavily
with pesticides.
Where organic bananas are grown, their eggs are predated by a
tiny Xenufens (Trichogrammatid) wasp. A gravid female wasp
attaches herself to the hindwing of an owl butterfly. If her host
is male, she transfers to the female when he mates. Once the
female butterfly lays her eggs, the wasp disembarks and pricks
tiny holes in the eggs in which to lay her own. The growing
wasps feed on the developing butterfly larvae. The larvae can be
controlled by these predators quite easily when no pesticides are
used.
Sightings at Cano Palma
Occasionally seen flying at
dusk in the area.
Newcomers to the compound often mistake owl butterflies for
bats. They are one of the most popular butterflies used in
butterfly farms, both in Costa Rica and world-wide.
References
Freitas, André V.L.; Benson, Woodruff W.; Marini-Filho, Onildo J.; de Carvalho, Roberta M. (1997). Territoriality by the dawn’s early light:
the Neotropical owl butterfly Caligo idomenaeus (Nymphalidae: Brassolinae). Retrieved February 26, 2008 from
http://www.doylegroup.harvard.edu/~carlo/JRL/34/PDF/34-014.pdf
Brest van Kempen, Carel (2006). Owlet Butterflies. Retrieved February 26, 2008 from http://rigorvitae.blogspot.com/2006/06/owletbutterflies.html
Davidson, Michael W. (2003). Tawny Owl Butterfly. Retrieved February 26, 2008 from
http://micro.magnet.fsu.edu/optics/olympusmicd/galleries/butterfly/tawnyowlo10.html
Canadian Organization for Tropical Education and Rainforest Conservation
www.coterc.org
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