Butterflies of the
Amazon and Andes
Teucer
Owl butterfly
Caligo teucer
LINNAEUS, 1758
Family - NYMPHALIDAE
subfamily -
MORPHINAE
Tribe - BRASSOLINI
subtribe -
BRASSOLINA
Caligo teucer, Satipo, Peru.
Introduction
A few decades ago the Owl butterflies were considered to be
members of a now defunct family, the Brassolidae. Following the
revisions of Erlich ( 1958 ) and Ackery ( 1984 ), all of the
butterflies with only two pairs of walking legs were placed within
the Nymphalidae. The Brassolidae were reduced in rank to a
subfamily Brassolinae, and then relegated further to become the
Brassolini - a tribe within the Morphinae.
The Morphinae includes
about 150 neotropical species, 93 of which are placed in the tribe
Brassolini. Of these, 73 are placed in the Brassolina - a subtribe
which includes
Blepolenis,
Brassolis, Dynastor,
Caligopsis, Catoblepia,
Dasyopthalma, Mielkella,
Opsiphanes, Mimoblepia,
Opoptera, Selenophanes,
Penetes,
Eryphanis,
Orobrassolis and
Caligo. All are crepuscular or
nocturnal in behaviour, although a few species also fly by day in
the darkest areas within their habitats. They are among the oldest
genera of butterflies on Earth - Brassolis
for example first evolved in the late Eocene Period, about 40
million years ago.
The 21
Caligo species
are known colloquially as Owl butterflies, due to the owl-like
false eyes, and the feathery appearance of the underside wings.
Various theories have been proposed to explain the presence of the
huge eyespots that adorn the underside hindwings of all species.
The butterflies rest for very long periods on tree trunks and can
be quite difficult to spot, but if accidentally disturbed by a
bird they take immediate flight and if seen from below with wings fully
open could feasibly be mistaken for an owl. When at rest however,
only one side of the wings can be seen at a time and the
appearance then is not owl-like. Another theory
states that the eyespot and surrounding dark areas are mimetic of
a species of tree frog that is said to rest on tree trunks where
Owl butterflies are seen. It is however difficult to imagine what
possible advantage a butterfly might have in resembling a tree
frog !
A more rational likelihood is
that the eyespot functions as a decoy. Caligo butterflies have a slow flapping
flight, so a bird could easily follow one to it's resting place.
Once it has settled however the mottled
patterning
provides the butterfly with
superb camouflage against the bark of a tree trunk,
with only the eyespot remaining prominent. Birds don't
direct their beaks aimlessly - they normally
aim for the head or body of a butterfly, but when the
butterfly is well camouflaged they would aim instead at the most obvious and
prominent feature, which in this case is the eyespot.
Caligo teucer
occurs from Colombia and Venezuela to Bolivia and Paraguay.
Caligo teucer, Satipo, Peru.
Habitats
This species inhabits rainforest and cloudforest habitats at altitudes between
about 500-1600m.
Lifecycle
Owl butterfly eggs are parasitised by tiny Trichogrammatid wasps
that ride from place to place on the hindwings of the butterflies.
They only leave the female's wings when she lays eggs, and then
return, to be transported to the next egg laying site. The eggs
laid by any individual female may be laid either singly, or in
groups of 20 or more, on
Heliconia leaves ( Heliconiaceae ).
The larvae are gregarious. Cannibalism does not apparently occur
despite the fact that aggregations may include small and
vulnerable 1st and 2nd instar larvae alongside fully grown
specimens. When full grown they are dull brown, marked with darker
longitudinal stripes. They have prominent forked tails, and a
crown of horns on their heads. The
larvae are nocturnal, and rest during daylight hours on dead
leaves at the base of the foodplants, where they are superbly
camouflaged. They appear to have some form of chemical defence, as
they are ignored by marauding Eciton
soldier ants.
The large stocky
pupa is pale brown with darker streaks and closely resembles a bit of dead
foliage. It is formed hanging by the cremaster from woody stems or amongst
clumps of dead leaves.
Caligo teucer, Satipo, Peru
Adult behaviour
Caligo butterflies are usually
encountered as singletons, flying just before dusk along narrow
trails.
They are strongly attracted to rotting plantain and other fruit on the
forest floor. If alarmed they fly off in an ungainly
fashion, with the flapping of their wings clearly audible.
Normally they fly only a few metres at a time, and settle on tree
trunks, but if they attempt to land on foliage they usually often
fail to maintain their grip, and are forced
to fly off again and settle elsewhere.
They continue flying throughout
the night, and are often attracted into buildings by
artificial lighting. Just before dawn they seek out narrow tree
trunks, on which they roost during daylight hours at a height of
between 1-2 metres above ground level. On particularly dull and damp
mornings they will continue flying, sometimes in quite open areas
along the edge of forest roads. At a site near Satipo in Peru I
have often seen this species imbibing at urine-tainted ground in
hot midday sunshine.
Owl butterflies
are known to live for up to 3 months in captivity but it is not
known how long they live in the wild.
Caligo teucer, Satipo, Peru
|
