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Butterflies of
the Amazon and Andes
Starry Night Cracker
Hamadryas laodamia
CRAMER, 1777
Family - NYMPHALIDAE
subfamily -
BIBLIDINAE
Tribe - BIBLIDINI
subtribe -
AGERONIINA
introduction
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habitats |
lifecycle |
adult behaviour
Hamadryas laodamia, male, Rio Madre
de Dios, Peru
Introduction
There are 20 members of the genus
Hamadryas,
commonly known as Crackers due to the ability of the males of several species to
produce a clearly audible sound which is 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. Both sexes are capable of
detecting the sound - their wings have tiny hollow cells covered in membranes
which vibrate in response to sound and stimulate nerve endings. The sound
probably functions as a warning to other
males that stray into each other's territory.
Photographing Cracker butterflies 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 at a time 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.
It is unusual to see the
butterflies on the ground. I spotted the butterfly in the above photograph
imbibing moisture at the edge of a rocky stream in Peru, surrounded by 50 or 60
Panacea prola and an assortment of other species
including Jemadia hewitsonii,
Adelpha jordani, and the beautiful day-flying moths
Urania leilus and Xanthiris flaveolata. As I
approached, the Panacea fanned their wings
displaying their red undersides, which act as an alarm signal causing the
entire swarm of butterflies to become airborne. After several minutes many of
the butterflies including the Hamadryas laodamia
returned, and I made another very cautious approach. Again the butterflies took
to the air, returning after several minutes in lower numbers. After several
unsuccessful approaches over a period of 2 hours or more, and with rain
beginning to fall, I had almost given up hope of a photograph, but was lucky to
squeeze off a single shot of this beautiful insect from a distance of about 2
metres. Ten seconds later the rain came pelting down and the butterflies all
disappeared.
The
common name Starry Night is derived from the painting by Vincent van Gogh.
Most
Hamadryas
species are found only in Central and South America, although 8 have been
recorded sporadically in the southern USA.
Hamadryas
laodamia
is distributed from Mexico to Peru.
Habitats
This species is confined to primary rainforest at altitudes between sea level
and about 900 metres.
Lifecycle
The eggs are white, and
laid in chains of up to a dozen, hanging from the underside of leaves. The
caterpillars when fully grown are reddish brown with a pale green band along the
back, and a broad white band above the spiracles. They have short rosetted
spines along the back, and a pair of longer spines on segments 3 and 10. The
head also bears a pair of long green horns. The caterpillars feed on
Dalechampia triphylla ( Euphorbiaceae ). The chrysalis resembles
a small withered leaf, and is pale brown in colour with a
pair of flattened curly head processes. It is
suspended by the cremaster from leaves or stems.
Adult behaviour
Like all
Hamadryas species
laodamia habitually basks on tree
trunks in a head-downward position and with the wings flattened
against the bark. They will bask in this position for long periods
to await potential mates. They commonly settle at a height of
about 2 metres but if disturbed they fly up and resettle high up, either on the same tree or on another nearby. They
remain high in the trees until the intruder leaves, and then
descend the trunk in a series of short flights, dropping a
short distance 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. They feed mainly on decomposing fruit, but as
described and illustrated above, they also
occasionally settle on the ground to imbibe mineralised moisture,
and are also attracted to human sweat.
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