Io moth

A moth with false eyes

The Io moth is a striking member of the giant silkmoth family, found across much of North America. Its most spectacular feature is a pair of large eyespots — round black and blue markings — on the hindwings, normally hidden beneath the forewings. When disturbed, the insect snaps them open to reveal these "eyes": the illusion of facing the stare of a large predator startles birds and other attackers. The male has yellow forewings, the female reddish-brown.

Habitat and distribution

It ranges from southern Canada to the southern United States, in varied habitats including woodland, prairie and sandy areas. Like many giant silkmoths, the adult is attracted to light sources and is active at night.

Life cycle and stinging caterpillar

The caterpillar is bright green with lateral stripes and, above all, is covered in tufts of branching spines connected to venom glands: contact causes a burning irritation like a nettle sting. As an adult the moth does not feed at all — it has no functional mouthparts — and lives only a few days, just long enough to reproduce.

Curiosities

The name comes from Io, a figure in Greek mythology loved by Zeus. The eyespot strategy, called "deimatic", is a classic example of defence that exploits visual deception without the animal actually being dangerous.

Conservation

The species is common and widespread and not considered threatened. As with many insects, habitat loss and pesticide use can nonetheless affect populations locally.