Why does a hawkmoth larva have a horn?
A Many hawkmoth caterpillars are embellished at their rear ends with a horn-like spine; in North America these larvae (and the moths that develop from them) are regularly known as hornworms. The role of these appendages remains something of a mystery. They are tough, but hardly rigid, so seemingly not much of a prickly deterrent against hungry birds. And since birds do not have an appreciation of cartoon stereotypes, they probably don’t mistake the horn for a stinger of some sort, either. Nevertheless, they are still used in self-defence. I once observed a blue tit attempt to snatch a fully grown lime hawkmoth caterpillar. It was at least 80mm long and as thick as my finger, and was ambling over the soil seeking a place to pupate. The larva thrashed about on the ground, madly writhing backwards and forwards with feather-ruffling vigour. I would not have wanted to be the diminutive bird on the receiving end of the sweeping blow of its tail spike.
Sporting the zingiest lime green, the eyed hawkmoth feeds on apple and crab apple.