Io Moth

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Scientific name

Automeris io (Fabricius)




Adults: Wingspan 5-8.7 cm; male forewings usually yellow, but may be red-brown, female forewings brown; hindwings of both sexes are yellow to brownish orange with yellow or orange margins and a large black and blue eyespot with a white dash in the center. Antennae of males are quite large and feathery compared to the females.

Larvae: Length longer than 2.5 cm; spiny; early instars red-orange, middle instars yellow (later turn green) with red and white lateral stripes. Larvae are highly gregarious, often found in quite large groups.

Eggs: Diameter about 1.5 mm. Have a micropyle rosette that turns black as eggs develop; usually laid in clusters of more than twenty.

Diagnostic features

Adult: Wingspan 5-8 cm, hindwing with large black to bluish eye spot with some white in center. Automeris io is sexually dimorphic; males with bright yellow forewings, body, and legs; females reddish brown forewings, body, and legs. Adults have vestigial mouthparts and do not feed.

Larvae: Spiny; first instar orange in color and gregarious; late instars yellow to green with red and white lateral stripe, usually solitary.


Native: Eastern North America, north to southern Canada, west to southern Arizona and south to Central America.


Palms: a variety of palms

Other: a wide variety of plants, including rose, cotton, hibiscus, azalea, willow, and clover, oaks, and other hardwoods

Additional comments

Io moth larvae are leaf feeders, gregarious in early instars then become solitary as they develop. They make a simple paper-like cocoon. Usually one generation in northern areas, 3-4 generations in Florida.

Io moth larvae can have three discrete color forms as they progress through their instars: yellow, blue-green, and green.

Io moth larvae have two types of poison spines. Remedies for relief of urticating patin include removal of inserted spines by the use of adhesive tape, followed by ice compacts, mentholated vaseline and/or an antihistamine.

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