Eacles imperialis

Adult male (underside) — Washington County (Suzanna Hendrix)

Mating adults — Tippecanoe County (Ron Needham)

Closeup of adult male antennae — Owen County (Rick Malad)

Closeup of adult female antennae — Tippecanoe County (Chris Joll)

Early instar caterpillars — Johnson County (JoAnne Cummings)

Early instar caterpillar — Pike County (Jeremy Ross)

Caterpillar feeding — Huntington County (Andrea Schwartz)

Last instar caterpillar — Monroe County (Martin Willimas)

Female laying eggs — Brown County (Rangel McThurman)

An Indiana Native

Eacles imperialis imperialis — Imperial Moth

(Drury, 1773)

Hodges# 7704

Etymology

Eacles: Unknown.

Imperialis: Latin for “of the empire.”

Pronunciation

ee-uh-kleez im-pihr-ee-al-iss im-pihr-ee-al-iss

Other Common Names

Great-plane tree moth. Hoosier author Gene Stratton Porter referred to the species as the “yellow emperor moth.”

Adult Size and Description

Wingspan: 80–170 mm (3.1–6.7 in)
Coloration and Patterning:

Both sets of wings pale to vibrant yellow with brick-red to plum to rust-brown basal patches, postmedial lines, and scattered dots on upper surfaces.
Females: Mostly yellow aside from red basal patches and postmedial lines
Extensive red areas. Particularly in basal areas and often from postmedial lines to margins on upper surfaces of both wings.
Upper surfaces of both wings of both genders with gray discal spots bordered in red

Sexual Dimorphism:

Females larger than males and with considerably less red coloration
Antennae quadripectinate on males and filiform on females
Males have a purplish patch on the end of the underside of their abdomen. Females lack this marking.

Defense Mechanisms:

Crypsis — Resembles leaf litter.

Range

This map illustrates documented North American records of Eacles imperialis imperialis as of 13 February 2021. The data used likely consists of combined records with the subspecies E. imperialis pini.

Documented record(s)

Conservation Status — NatureServe Rankings

Secure 5: Secure NR: Not ranked

Historical References

Included within Dru Drury’s three-volume Illustrations of Natural History, Wherein are Exhibited Upwards of 240 Figures of Exotic Insects, published between 1770 and 1787, was a plate featuring male and female imperial moths.

Floral Associates

Eacles imperialis imperialis caterpillars are the largest in Indiana. Polyphagous, they eat the foliage of several families and genera of native trees, including their namesake hickories (Carya spp.) 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: Ericales
Ebenaceae	Diospyros virginiana	persimmon
Order: Fabales
Fabaceae	Gleditsia spp.	water and honey locusts
Order: Fagales
Betulaceae	Alnus spp.	alders
	Betula spp.	birches
Fagaceae	Castanea dentata	American chestnut
	Fagus grandifolia	American beech
	Quercus spp.	oaks
Juglandaceae	Carya spp.	hickories
	Juglans spp.	black walnut and butternut
Order: Gentianales
Rubiaceae	Cephalanthus occidentalis	buttonbush
Order: Hamamelidales
Platanaceae	Platanus occidentalis	American sycamore
Order: Laurales
Lauraceae	Sassafras albidum	sassafras
Order: Malvales
Tiliaceae	Tilia americana	American basswood
Order: Pinales
Cupressaceae	Juniperus spp.	junipers
Pinaceae	Larix spp.	larch, aka tamarack
	Picea spp.	spruce
	Pinus	pines
	Tsuga canadensis	eastern hemlock
Order: Poales
Poaceae	Zea mays	corn
Order: Rosales
Moraceae	Morus spp.	mulberries
Rosaceae	Prunus spp.	cherries
Ulmaceae	Ulmus spp.	elms
Order: Salicales
Salicaceae	Populus spp.	poplars
	Salix spp.	willows
Order: Sapindales
Aceraceae	Acer spp.	maples
Anacardiaceae	Rhus spp.	sumacs
Hippocastanaceae	Aesculus spp.	buckeyes
Order: Saxifragales
Altingiaceae	Liquidambar styraciflua	American sweetgum

Imperial Moth (Eacles imperialis imperialis) in Indiana

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

Occurrences by County

Counties recorded: 65 of 92

Top counties/#of records:
Washington: 96
Brown: 38
Monroe: 35
Scott: 33
Owen: 24
Hamilton: 22
Morgan: 18

species present icon GAIN LP documented in county

Sightings by Month

Earliest live adult: Eric Young, Dubois County on 02 June 2018
Latest live adult observation: Jessica Pratt-Glasener, Hamilton County on 22 September 2019

Total Sightings by Year

Total Number of observations (all years combined): 384
Number of field observers: 181

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).