Invertebrates
Io Moth
Automeris io · also called io moths
A bird pecks curiously at what looks like a plain yellow leaf, and the io moth responds instantly, flashing forward its forewings to reveal two enormous blue-black eyespots, a startling bluff sharp enough to send most predators fleeing.
Overview
The io moth, Automeris io, is a strikingly patterned giant silk moth native to forest and grassland habitat across the eastern and central United States. Its dramatic hindwing eyespot display, venomous spine-covered caterpillar, and complete inability to feed as an adult make it one of the more genuinely eventful and defensively equipped moths in North America.
A double defence, front and back
Between a caterpillar covered in stinging spines and an adult capable of flashing startling false eyes on command, the io moth has built a defensive strategy that follows it through every stage of its short, feeding-free adult life.
Status
Least Concern — widespread and common across suitable forest and grassland habitat throughout the eastern and central United States.
Io Moth: common questions
Why does the io moth have such large eyespots on its hindwings?
When disturbed, an io moth suddenly flashes its forewings forward to reveal two large blue-black eyespots on the hindwings, a startling visual bluff that mimics the eyes of a much larger animal and can momentarily confuse or deter an approaching predator long enough for the moth to escape.
Is it true that the io moth caterpillar can sting?
Yes, the io moth caterpillar is covered in branching spines that deliver a genuinely painful sting on contact, injecting venom that causes burning, swelling, and irritation, making it one of several stinging caterpillars in North America worth learning to recognise and avoid touching.
How can you tell a male io moth from a female?
A male io moth has bright yellow forewings, while the female shows a darker reddish-brown to purplish colouration, a pronounced and easily noticeable difference in appearance between the sexes that is more dramatic than in several other giant silk moth species.
Do adult io moths eat anything?
No, an adult io moth has no functional feeding mouthparts and survives entirely on fat reserves stored during its caterpillar stage, living only about a week as a winged adult whose sole purpose during that time is to find a mate and reproduce.