National Moth Week: Io Moth (Automeris io)

Adult Io Moth with wings spread to show eyespots. iNaturalist observation by ceharlan CC BY-NC 4.0

When a kid, I learned a bit about mythology through my Golden Guides on insects, butterflies, and moths. These small, battered reference books went with me most every time I explored the fields and woods around my house, and they helped instill a lifelong interest in entomology.

Adult Io Moth with wings tucked in Miami-Dade County. iNaturalist observation by miaminaturegirl CC BY-NC 4.0

Why am I telling you this? Because that’s how I learned about the Io moth, a beauty named after a mythological Greek maiden, according to my trusty guide. However, according to subsequent research, Io was more than a simple maiden—she was a goddess, first priestess of Hera and wife of Zeus, god of thunder and lightning. That’s kind of a big deal.

The Io moth is kind of a big deal, too, with its beautiful wing spots, attractive coloration, and wingspan up to more than 3 inches, not to mention it’s the moth of choice for the National Moth Week logo. Part of the Saturniidae family, which includes the largest moths in North America (including Luna and Polyphemus moths), the Io moth shares several traits with its near relatives, such as adults having very hairy bodies and caterpillars sporting venomous stinging hairs you do not want to touch.

Io Moth caterpillar on native Blackberry (Rubus sp.) in Split Oak Forest WEA. Photo by Valerie Anderson.

The Io moth is found from southern Canada throughout the eastern U.S. and as far southwest as Mexico and northwest as Montana. And, unfortunately, like many invertebrates, its population has decreased noticeably across its range, as stated in this research paper by University of Florida’s IFAS. Spend a little time with this paper—It has a great series of photos depicting the moth’s full life cycle, from egg to caterpillar to moth.

The adult moths do not eat, but the caterpillars definitely do. They’re polyphagous, so many trees and shrubs serve as larval hosts. Research shows the caterpillars feed on at least a couple dozen species of trees and shrubs, with regional preferences. For example, in south Florida, the spiny caterpillars gravitate to royal Poinciana, hibiscus, red mangrove and Washington fan palm trees, among others. In other areas of Florida, they can be found on oak, hackberry, wax myrtle, and various other trees in deciduous forests and suburban areas.

Do you have any of these trees in your neighborhood? If so, you just might have some of these great moths cruising around the place. Like most moths, Io moths are nocturnal, so your best bet to spot one is to head outside with a flashlight in the night. If you find any moths on your explorations, be sure to share your photos on the National Moth Week citizen science project through iNaturalist.

by Laura Bennett-Kimble of Passionflower Chapter, edited by Valerie Anderson