Hamadryas amphinome, Yarinacocha, Ucayali, Peru – Adrian Hoskins
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. The blue colour is produced by light diffracting from microscopic prismatic ridges on the surface of the wing scales. The colour varies slightly according to the quality, intensity and angle of the light, so can appear as sky blue, cyan or even greenish in hue.
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.
The common name Red Cracker refers to the colour of the underside hindwings.Hamadryas amphinome is distributed from Mexico to Peru.
Hamadryas amphinome, Yarinacocha, Ucayali, Peru – Adrian Hoskins
Habitats
The Red Cracker is found in secondary or disturbed rainforest habitats at altitudes between about 0-1500 metres. It also occurs in dry or humid deciduous forests where it can often be abundant. In Guanacaste for example I found several basking on mango trees in a small orchard in the rainy season ( July ), together with februa, feronia and glauconome.
Hamadryas amphinome, Yarinacocha, Ucayali, Peru – Adrian Hoskins
Lifecycle
The eggs are white, and laid in a pendant chain of up to a dozen, hanging from the underside of a leaf. The larvae when fully grown are black, with yellow marbling along the back, and have multi-branched spines that are black except for those on the middle section which are orange.
They feed gregariously on Dalechampia scandens ( Euphorbiaceae ). The chrysalis strongly resembles a small withered leaf. It varies in colour from green to dark brown, and has a pair of flattened wavy head horns that are about half as long as the body. It is suspended by the cremaster from a leaf or stem.
Hamadryas amphinome, Rio Madre de Dios, Peru -Adrian Hoskins
Adult behaviour
Hamadryas amphinome 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.
There they remain until the threat passes, after which they 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. They feed mainly on decomposing fruit.
Hamadryas amphinome, Yarinacocha, Ucayali, Peru – Adrian Hoskins