Butterflies at Home

Imperial Moth

The Imperial Moth (Eacles imperialis), and their regional morphs, subspecies, and sibling species range from Argentina to Canada, and from the Rocky Mountains to the Atlantic Coast of the United States. It is considered a giant silkworm moth, mostly yellow with spots, lines and splotches of light to dark brown. However, its appearance and coloration can vary widely.

Adult Imperial Moths have a wingspan of approximately 3–7 inches, and emerge once a year from the ground to mate. After mating, females lay hundreds of eggs on a wide variety of trees. The male and female have different markings, as shown in the photos below. The male is more heavily marked, with blotches of red, brown, and purple. Females are larger than the males, and are more yellowish in color.

The Imperial Moth larva (caterpillar) is often brown with white oblong spots circled in black, although significant variation in coloration does occur. Full-grown, 5th instar larvae measure about 3.5 inches.

Imperial Moth (male)
Male Imperial Moth
Imperial Moth (female)
Female Imperial Moth
Imperial Moth caterpillar (courtesy of the US. Fish & Wildlife Service)
Imperial Moth caterpillar