Automeris io io

Adult male — Hamilton County (Connor Foley)

Adult male hindwing view — Morgan County (Tim Bailey)

Adult male underside view — Porter County (Theresa Dixon)

Adult female forewings — Greene County (Amanda Staggs)

Adult female fore and hindwing view — Monroe County (Tracey Setze)

Adult female and male side-by-side — Hamilton County (Dan McCord)

Close up of male antennae — Vermillion County (Tiffany Revesz)

Closeup of eye-spot — Scott County (Brian Lowry)

Early instar caterpillars — Monroe County (Tracey Setze)

Mid-instar caterpillars — Hamilton County (Amanda Smith)

Late instar caterpillars — Scott County (Brian Lowry)

Late instar caterpillar — Hendricks County (Tina Price)

An Indiana Native

Automeris io io — Io Moth

(Fabricius, 1775)

Hodges# 7746

Etymology

Automeris: Combines the Greek auto meaning “self” and meris meaning “divided.”

Io: Derived from Greek mythology, Io, princess of Argos, was a mortal woman with whom Zeus fell in love. Io is also the innermost and third largest of Jupiter’s moons.

Pronunciation

ahw-toe-mihr-is eye-oh eye-oh

Other Common Names

Hoosier author Gene Stratton Porter sometimes referred to io moths as “Hera of the Corn,” meaning “goddess or queen of the corn,” which was in reference to corn being an occasional host plant to the caterpillars (Stratton-Porter 1921).

Gene Stratton Porter Io Painting — Gene Stratton-Porter’s watercolor illustration of male and female io moths (*Automeris io io*)

Adult Size and Description

Wingspan: 50–85 mm (2–3.3 in)
Coloration and Patterning:

Male fore and hind wings are bright yellow. Female forewings are pinkish-brown to orange-brown, and hindwings are dark yellow.
Forewings of both genders contain reddish-brown discal spots, antemedial, postmedial, and subterminal lines. The wavy, often segmented lines, particularly the subterminal lines, may be faint to nearly absent. In females, spots and lines often highlighted with yellow-brown.
Hindwings of both genders have a conspicuous blue, discal “eyespot” that is edged in black and contains a white “pupil” to resemble mammalian eyes. A thin, reddish-brown postmedial line flanks each eyespot, and a broad, red, subterminal line extends down the inner margin to the base of each hind wing.

Sexual Dimorphism:

Coloration (see above)
Females are larger than males.
Antennae are quadripectinate on males and bipectinate on females.

Defense Mechanisms:

Crypsis — Leaf coloration
Batesian Mimicry — Discal eyespots
Deimatic Display — Flashing hindwing eyespots to frighten predators

Range

This map illustrates documented North American records of Automeris io io as of 17 May 2021.

Documented record(s)

Conservation Status — NatureServe Rankings

Secure 5: Secure 4: Apparently secure NR: Not ranked

Floral Associates

Automeris io io caterpillars are polyphagous and able to eat the foliage of several families and genera of native trees. Adults lack a digestive system, do not eat, and exist solely for reproduction.

Family	Taxonomic Name	Common Name
Known Larval Food Sources in Indiana
Order: Aquifoliales
Aquifoliaceae	Ilex spp.	hollies
Order: Cornales
Cornaceae	Cornus spp.	dogwoods
Nyssaceae	Nyssa sylvatica	black gum, aka tupelo
Order: Dipsicales
Adoxaceae	Viburnum spp.	viburnums
Caprifoliaceae	Symphoricarpos spp.	snowberries
Order: Ericales
Ebenaceae	Diospyros virginiana	persimmon
Ericaceae	Rhododendron spp.	azaleas and rhododendrons
Order: Fabales
Fabaceae	Albizia julibrissin	Persian silk tree
	Amorpha canescens	lead plant
	Baptisia spp.	wild indigos
	Chamaecrista spp.	partridge peas
	Galactia volubilis	downy milk pea
	Gleditsia spp.	water and honey locusts
	Glycyrrhiza lepidota	American licorice
	Lespedeza spp.	lespedezas
	Melilotus spp.	sweet clovers
	Phaseolus polystachios	thicket bean
	Robinia spp.	locusts
	Trifolium spp.	clovers
	Wisteria spp.	wisterias
Order: Fagales
Betulaceae	Betula spp.	birches
	Carpinus caroliniana	musclewood, aka blue beech
	Corylus americana	American hazelnut
	Ostrya virginiana	hop-hornbeam, aka ironwood
Fagaceae	Fagus grandifolia	American beech
	Quercus spp.	oaks
Juglandaceae	Carya spp.	hickories
	Juglans spp.	black walnut and butternut
Myricaceae	Comptonia peregrina	sweet fern
Order: Hamamelidales
Platanaceae	Platanus occidentalis	American sycamore
Order: Lamiales
Oleaceae	Fraxinus spp.	ashes
	Ligustrum spp.	privets
Order: Laurales
Lauraceae	Sassafras albidum	sassafras
Order: Magnoliales
Magnoliaceae	Liriodendron tulipifera	tulip tree
	Magnolia spp.	magnolias
Order: Malvales
Malvaceae	Hibiscus spp.	hibiscus
Tiliaceae	Tilia americana	American basswood
Order: Myrtales
Lythraceae	Lythrum spp.	loosestrifes
Order: Pinales
Pinaceae	Abies spp.	firs
Order: Poales
Poaceae	Cynodon dactylon	Bermuda grass
	Zea mays	corn
Order: Rosales
Cannabaceae	Humulus spp.	hops
Moraceae	Ficus carica	common fig
	Morus spp.	mulberries
Rosaceae	Amelanchier spp.	serviceberries
	Crataegus spp.	hawthorns
	Malus spp.	apples and crabapples
	Physocarpus opulifolius	ninebark
	Prunus spp.	cherries
	Pyrus spp.	pears
	Rosa spp.	roses
	Rubus spp.	blackberries, dewberries, and raspberries
	Spirea spp.	meadowsweets
Ulmaceae	Celtis spp.	hackberries
	Ulmus spp.	elms
Order: Salicales
Salicaceae	Populus spp.	poplars
	Salix spp.	willows
Order: Sapindales
Aceraceae	Acer spp.	maples
Order: Saxifragales
Altingiaceae	Liquidambar styraciflua	American sweetgum
Grossulariaceae	Ribes spp.	currants and gooseberries

Io Moth (Automeris io io) in Indiana

The map, graph(s), and data below represent the Indiana sightings of Automeris io io as of 21 November 2024, confirmed through photographic evidence by individuals who contributed to the Great American IN Nature Lepidoptera Project (GAIN LP).

Occurrences by County

Counties recorded: 45 of 92

Top counties/#of records:
Brown: 70
Monroe: 32
Hamilton: 29
Scott: 17
Porter: 14
Washington: 13
Hendricks: 10

species present icon GAIN LP documented in county

Sightings by Month

Earliest live adult: Anthony Lara, Grant County on 18 May 2018
Latest live adult observation: Carole Mitchell, Elkhart County on 20 July 2019

Total Sightings by Year

Total Number of observations (all years combined): 208
Number of field observers: 86

Sightings by Gender

Image Gallery

The images and records below were all submitted by individuals through the Great American Indiana Nature Lepidoptera Project (GAIN LP).

Additional Sources

Stratton-Porter, G., 1921. Moths of the Limberlost, with water color and photographic illustrations from life. Garden City, NY and London: Doubleday, Page & Company.