Strange but true ! Next >> Odd postures ! There can be few butterflies or moths as weird as this creature which I discovered in the rainforests of Trinidad. While walking along a trail my attention was caught by what appeared to be a dead leaf that seemed to have fallen and landed on a broad green leaf. A spider appeared to be squatting in the middle of the dead leaf, but somehow it all looked a bit too symmetrical. Siculodes aurorula , Arima valley, Trinidad © Adrian Hoskins Closer examination revealed that the "dead leaf" was in fact the wings of a moth, and the "spider" was it's body and legs. It had adopted an extremely odd posture, with it's body upright, and its legs and outstretched wings held in a vertical plane. The wings are a marvellous example of camouflage - perfectly disguised as a dead leaf, complete with windows to simulate the nibblings of insects, and spotted with dark areas that could easily be mistaken for leaf mould. Identification proved extremely difficult as there is hardly any published material about neotropical moths available for reference. For many years I was completely mystified by the insect, but it was finally identified 10 years later by Mike Shaffer of the British Natural History Museum, as Siculodes aurorula , a member of the Thyrididae. My specimen was the first ever recorded in Trinidad. My photograph of the living moth finally revealed the purpose of its incredibly long legs. These had long puzzled entomologists who had studied the museum specimen. The moth needed them so that it could prop itself up in this very odd upright posture. The pose is almost threatening. Why would a moth evolve such a strange posture ? Perhaps when viewed from the front it might appear so scary that it would frighten off a small avian or reptilian predator ? Perhaps it simply needs to raise itself clear of the substrate to avoid getting stuck to it when the leaves are wet with rain ? Unrelated species which look identical ! The mimicry theory postulated by Henry Walter Bates states that by a process of natural selection, many edible butterfly species have evolved wing patterns which mimic those of distasteful species. The mimics benefit because any bird which has suffered the unpleasant experience of tasting an unpalatable species remembers the pattern and is fooled into leaving the edible mimics alone. By way of example, t he Heliconiine genus Eueides comprises of 12 medium sized butterflies which share almost identical anatomical and morphological features, but which differ greatly in colouration and patterning. Some, like isabella appear to be mimics of orange / black banded Ithomiines, while others including aliphera and lineata are very similar to Dryas iulia in appearance. Yet others, such as vibilia , closely resemble Actinote species. Eueides heliconioides falls into yet another group that strongly resemble Laparus species. In all these cases the "models" are considered to be distasteful to avian predators, while all the "mimics" are believed to be edible. This is called Batesian Mimicry. Müller later theorised that unrelated and unpalatable butterflies also mimic each other to increase each individual species' chance of avoiding attack. Many orange / black banded species from the subfamilies Danainae, Ithomiinae, Riodinidae, Nymphalinae, Heliconiinae, Papilioninae, Pierinae, Dismorphiinae and Acraeini are so similar that they are considered to be involved in a "mimicry ring" known as the tiger complex, in which convergent evolution has caused once dissimilar taxa to become almost identical. It is often the case that males mimic one unpalatable species, while the females mimic another entirely different one! Illustrated below are a pair of Müllerian mimics which were flying together in cloudforest habitat at Shima in the Peruvian Andes. Eresia eunice ( Nymphalinae ) © Adrian Hoskins Eueides isabella dissoluta ( Heliconiinae ) © Adrian Hoskins Hiding from humans ! Butterflies do some strange things to elude attention. The Zebra Hairstreak Arawacus separata has a pattern of stripes which creates the illusion that it is facing back to front. It enhances the illusion by immediately turning to face the opposite direction as soon as it lands on a leaf. There it remains totally motionless until approached, at which point it slowly but deliberately rotates to present the observer with a view of it's posterior ! Arawacus separata © Adrian Hoskins The pattern of striped directs the eye towards the "false antennae" which are actually small tails on the hindwings. It reinforces the illusion that it's tail is it's head, by turning to face the opposite direction as soon as it lands on a leaf. It even jiggles it's wings slightly to make the false antennae move ! It's all part of a trick to divert bird attacks away from the head, and allow the butterfly to escape. Clever eh ? Another South American species, the Mosaic Colobura dirce , spends long periods perching motionless on tree trunks. It is normally a very tame insect, allowing humans to approach closely, but if deliberately disturbed, instead of flying, it scuttles around to the opposite side of the tree trunk to hide. If the observer follows it, the butterfly runs back again, and repeated disturbance causes it to literally run around in circles in a chase around the tree trunk ! Strange feeding habits ! In temperate countries most adult butterflies feed on flower nectar, although some will visit sap runs, or imbibe dissolved mineral salts from dung, damp earth or carrion. In the tropics many Nymphalids feed at rotting fruit, while Swallowtails and Sulphurs prefer to drink from urine-soaked ground, and many Hesperiine skippers are noted for feeding at bird droppings. Rotting fish are a popular food source for Agrias and certain other species in South America, where I've also seen Ithomiine Glasswings feeding on the corpses of flies. In Malaysia, I've observed an Allotinus species feeding directly from the honey glands of aphids. In Ecuador I've watched the beautiful Junea doraete gorging itself on the corpse of a snake, and found the stunning metalmark Necyria bellona feeding on the corpse of a toad. Venezuela produced something even more interesting - the gorgeous long-tailed metalmark known as the Blue Doctor Rhetus periander , which was seen feeding on the corpse of a giant tarantula. Blue Doctor Rhetus periander © Adrian Hoskins One of the strangest habits however is that of the brilliant orange Julia Dryas iulia , which is quite content to feed at nectar in Costa Rica, or to imbibe dissolved minerals from mud in Ecuador, but in parts of Brazil groups of these butterflies are regularly seen sipping the liquid in the corner of the eye of the yellow-throated caiman ! Ne xt >>

