How to identify the White-marked Tussock Moth
The adult male is a small, grayish-brown moth with a wingspan around 2.5 to 3.5 cm (about 1 to 1.4 inches). The forewings are gray-brown with wavy darker bands and a small white spot near the lower rear corner, the "white mark" that gives the moth its name. The female is the surprise: she is wingless, gray and grublike, and never flies. After emerging she stays on her cocoon, releases pheromones, mates, and lays a frothy white egg mass right there. The caterpillar is far more eye-catching than either adult.
Where the White-marked Tussock Moth lives
This is a wide-ranging moth of eastern North America, found in forests, parks, street trees and suburban yards. The open records concentrate it in North Carolina, New York, Virginia, Georgia and Michigan. Because the caterpillars feed on a huge range of trees, the species turns up almost anywhere there are hardwoods, including city plantings.
When the White-marked Tussock Moth flies
There are usually two or more generations per year, so the flightless females and flying males appear over a long season. In the records the adults peak from June through September. With overlapping broods, you can find adults, caterpillars and egg masses across much of the summer and into early fall.
Caterpillar, host plants and life cycle
The caterpillar is one of the most recognizable in North America: it has a bright red head, two long black "pencil" tufts pointing forward, a single black tuft at the rear, and four dense white-to-cream tufts (tussocks) on its back. It is a generalist that feeds on many hardwoods, including oak, maple, birch, elm, willow and apple, and it can occasionally defoliate ornamental trees. Those hairs are urticating and can irritate skin or cause an itchy rash in sensitive people, so don't handle it. The life cycle runs from frothy overwintering egg mass to tufted caterpillar to cocoon, with the wingless female completing the loop right where she pupated.
How to see a White-marked Tussock Moth at night
Only the males come to light, since the females cannot fly, so a light session will turn up the small gray-brown males rather than the more famous caterpillar. Hang a white sheet and use a UV (blacklight) or mercury-vapor lamp; UV draws far more moths than a white LED. Moths gather at lights because the bright source disrupts their flight orientation, so keep the light steady against a pale backdrop and check the first hours after dark. To find the dramatic caterpillar instead, search tree trunks and leaves by day. Not sure what you are looking at? Try our what moth is this guide or compare with the Banded Tussock Moth.