Luminary Oddities · Natural history & art
Io moth
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 accountAt a glance
- Adult feeding ↘
- Adults do not feed [1]
Identity
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]
Morphology and identification
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]
Distribution and habitat
Its range extends from southern Canada across the eastern United States into eastern Mexico. [1]
Life cycle
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]
Feeding and host plants
Larvae use numerous woody hosts, including maples, hickories, hackberries and cherries. Adults do not feed. [1]
Behaviour
Young larvae follow silk trails in single-file groups. Disturbed adults move the forewings forward to reveal the hindwing eyespots. [1]
Distinctive biology
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]
Nomenclature and history
Fabricius described the moth as Bombyx io in 1775. [1]
Sources and further reading
- Io Moth Automeris io (Fabricius) (Insecta: Lepidoptera: Saturniidae) ↗
Donald W. Hall; University of Florida / IFAS · Accessed 2026-10-11
- Larvae of Io Moth, Automeris io, on the Coral Bean, Erythrina herbacea, in Florida—the Limitations of Polyphagy ↗
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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