How to identify an Imperial Moth
The Imperial Moth is hard to mistake. The base color is a bright lemon-to-mustard yellow, overlaid with patches and speckling of rusty purple-brown that vary a lot from moth to moth - some are mostly yellow, others heavily clouded with purple. The wings are broad and slightly scalloped, and the body is stout and furry. Wingspan runs from about 3 inches up to 5.5 inches, with females usually larger and yellower and males more heavily marked. There are no tails and no big eyespots, so the look is more of a patchwork dead leaf than the long-tailed silhouette of a Regal Moth.
Where it lives
This is a moth of eastern and southern woodlands. In open records it shows up most in North Carolina, Virginia, Georgia, Florida, and Texas, and it ranges broadly across the eastern United States wherever its host trees grow. It favors mixed forests, wooded suburbs, and tree-lined neighborhoods rather than open grassland. See what else flies in North Carolina or Virginia through the summer.
When it flies
Peak adult flight is July and August. Farther south the season can stretch a little, but if you want the best odds, plan your light nights for mid- to late summer. Adults are nocturnal and come to light; you will not see them nectaring at flowers because they do not feed.
Caterpillars, host plants, and life cycle
Imperial Moth caterpillars are large and variable in color, from green to brown to a burnt-orange form, dotted with pale spots and short spines, and they can reach the size of a finger. They feed on a wide range of trees including pine, oak, maple, sweetgum, and sassafras. After feeding through late summer the caterpillar burrows into the soil to pupate - this moth does not spin a tough aboveground cocoon - and overwinters underground before emerging the next summer. There is generally one generation per year in the north and sometimes more in the deep south.
How to see one at night
Set up a light after dark on a warm, still July or August night. A UV (blacklight) or mercury-vapor lamp aimed at a white sheet pulls in far more moths than a plain white LED, because moths respond most strongly to short-wavelength light. They are not really hunting the bulb - the leading explanation is that artificial light scrambles the flight orientation they normally hold against the moon, so they circle and settle nearby. Warm, humid, moonless nights are best - our guide to a good night for moths walks through the weather. Curious which giant silk moths share your yard? Try the Tonight's Moths predictor for your location and date.