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Automeris io
Lepidoptera / Saturniidae
The Io moth conceals a pair of conspicuous hindwing eyespots beneath forewings that vary with sex and population. Its green caterpillars carry branching, stinging spines.
Read the species account
Automeris io is a North American silk moth in Saturniidae. The reddish form historically called lilith occurs beyond the southeastern United States; Tuskes and colleagues treated that name as a synonym rather than a geographically coherent subspecies. [1]
Females have red-brown forewings and slender-looking antennae; males have broader comb-like antennae and yellow, tawny or orange-brown forewings. Yellow males predominate farther north. Each hindwing bears a large dark eyespot with a contrasting pale highlight. [1]
Its range extends from southern Canada across the eastern United States into eastern Mexico. [1]
In Sourakov’s Gainesville rearing series, larvae passed through seven instars. Surviving larvae from the second experiment reached pupation sooner on coral bean than on water oak, but produced smaller adults. [2]
Larvae use numerous woody hosts, including maples, hickories, hackberries and cherries. Adults do not feed. [1]
Young larvae follow silk trails in single-file groups. Disturbed adults move the forewings forward to reveal the hindwing eyespots. [1]
The Gainesville feeding experiments found high mortality among young larvae on Erythrina herbacea and tender Quercus nigra leaves, whereas mature oak leaves supported substantially better survival. Applying methanol-extracted coral-bean compounds to oak leaves did not cause mortality in the tested larvae. Sourakov proposed that leaf water content contributed to the poorer survival. [2]
Fabricius described the moth as Bombyx io in 1775. [1]
Donald W. Hall; University of Florida / IFAS · Accessed 2026-10-11
Andrei Sourakov; Journal of the Lepidopterists’ Society 67(4), 291–298 (2013) · Accessed 2026-10-11
Sources checked 2026-10-11. Illustrations · Luminary Oddities.
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