Butterflies of
the Amazon and Andes
Boisduval's Cracker
Hamadryas amphichloe
BOISDUVAL, 1870
Family - NYMPHALIDAE
subfamily -
BIBLIDINAE
Tribe - BIBLIDINI
subtribe -
AGERONIINA
Hamadryas amphichloe Ecuador
© Tony Hoare
Introduction
There are 20 members of the genus
Hamadryas. Most are
found only in Central and South America, although 8 have been recorded
sporadically in the southern USA.
The butterflies are
commonly known as Crackers due to the ability of the males of several species to
produce a sound similar to the crackling of bacon in a
frying pan.
The sound is produced as the butterflies take off, and is made by twanging a
pair of spiny rods at the tip of the abdomen
against bristles on the anal
claspers. Only males can produce the sound, but both sexes can detect it - their
wings have tiny hollow cells covered in membranes that vibrate in response to
sound, and stimulate nerve endings. The purpose of the sound is not known. It
may possibly
deter competing males from occupying the same territory, or could act as a
trigger to initiate the first response from a female during courtship.
All Hamadryas
species have a beautiful calico pattern on the upperside. In many there is a series of
submarginal ocelli on the hindwings, and distinct kidney-shaped stigmata in the
discal cells of fore and hind wings.
In several species such
as februa
and
glauconome
the ground colour is greyish and the pattern acts as an extremely effective
camouflage against the bark of trees. In others such as
amphinome,
laodamia and
velutina
the wings are velvety black with a blue sheen and a pattern of bright blue spots.
Photographing Hamadryas can be a frustrating
experience, as both sexes spend most of their time basking high up on tree
trunks, often 10 metres or more above the ground. They sit there for hours with wings outspread, always facing downwards to keep a watchful
eye for potential mates. At times they descend and bask much lower down, at a
height of just a couple of metres,
but at the slightest
disturbance they immediately fly back to the tree top. They remain there until
the intruder has left the vicinity, and then descend the tree trunk in a series
of short hopping flights, dropping a short distance each time until after half
an hour or so they have resumed their original position.
Hamadryas
amphichloe
is distributed from Panama to Peru, and also occurs in Puerto Rico and the
Dominican Republic.
Habitats
This species is found in rainforest and deciduous forest habitats at altitudes
between sea level and about 1200 metres.
Lifecycle
I have no data specific
to amphichloe. The eggs of
Hamadryas are laid either singly or in pendant chains beneath leaves,
according to species. Likewise the larvae may be solitary or gregarious in
behaviour. Most species feed as larvae on Dalechampia
( Euphorbiaceae ).
Adult behaviour
Hamadryas
amphichloe is often seen basking on tree
trunks, adopting a head-downward posture, with the wings flattened
against the bark. The butterflies will bask in this position for long periods
to await potential mates. They commonly settle at a height of
about 2m but if disturbed immediately take flight. After a few
seconds they resettle, usually
higher up on the same tree trunk. They
remain there until the threat passes, and then
descend the tree trunk in a series of short flights, dropping
lower each time until after several minutes they resume
their original position.
The
butterflies are active from sunrise to sunset, and are rarely seen
away from tree trunks, but also sometimes bask on rock faces or
tree foliage.
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