Whilst photographing this striking butterfly – The Common Tit (Hypolycaena erylus himavantus) in Thailand – I noticed that it was moving the tails at the end of its wings. The movement was quite noticeable; the little black ‘tails’ with white tips, moving up and down. This behaviour not only draws attention to the back of the animal, but the tails also look surprisingly like antennae. According to the ‘false head’ hypothesis, butterflies such as these – lycaenids – have evolved the appearance of a false head at the back end, so that predators such as birds, will direct their attacks towards this, the less vulnerable part of the insect (1). The effect is presumably reinforced by the eye-spots at the end of the hind-wings, which may also tempt birds to peck at those places (and not at the head). The tails are best seen in profile, when the black spots on the hindwings – false eyes – are also most apparent (2). So the butterfly becomes a sort of pushmi-pullyu (push-me—pull-you) creature, a Doctor Dolittle animal with two front ends that looks like it could go either way!
The male H. erylus himavantus has purple-blue coloured wings with a circular black brand (or circle) on the upperside of the fore-wings, just visible in these photos (above and below); whilst the female has brown wings without a black spot (2). The black circular mark on the forewing (below) is not particularly distinct, and is not a prominent eye-spot, as such. What it’s function is I have no idea.
The remarkable thing about this small blue butterfly, is that the larvae are attended by Weaver ants; the ants protect the larvae in exchange for ‘nectar’ secreted by the larvae via a special organ on their back (2). The ants in effect stand guard around the butterfly larvae in exchange for the delicious liquid produced by the caterpillars! Such associations, between lycaenids and ants are very common, and the butterflies have evolved many interesting ways of manipulating the ants to their (sometimes mutual) advantage (3, 4). Incredibly, the lycaenid butterfly larvae produce a so-called ‘appeasement song’ – low vibrations which are picked up by the ants via the substrate (plant) – which stop the ants from attacking them, and perhaps even summon the ants if the larvae are threatened! The pupae also make sounds which have been shown to likewise attract ants and keep them close by to guard the immobile pupa.
These photographs were taken in December 2014, at Doi Chiang Dao, Chiang Mai Province, northern Thailand.
1. Robbins, Robert K. “The” false head” hypothesis: predation and wing pattern variation of lycaenid butterflies.” American Naturalist (1981): 770-775.
3. Pierce, Naomi E., et al. “The ecology and evolution of ant association in the Lycaenidae (Lepidoptera).” Annual review of entomology 47.1 (2002): 733-771.