About 30 species of this subfamily are found in North America. Adults are usually quite hairy and generally have subdued colors in shades of brown, gray, or white. The antennae are comblike (bipectinate). Females frequently are larger than males, flightless, and may have the wings reduced or absent. As with the hairs on the caterpillars, the hair tufts on the end of the adult female’s abdomen may be skin-irritating if touched.
The caterpillars tend to be brightly colored with distinctive groups of hair tufts, some short and some long, often with 2 long tufts in the front and 2 or 3 at the hind end. The elongated clumps are sometimes called "pencils." Some species have hollow, barbed hairs that sting with toxic spines. The caterpillars incorporate those hairs into the cocoon for protection.
Some examples of species in this subfamily include the white-marked tussock moth (Orgyia leucostigma), whose larvae damage orchard trees, and the exotic, invasive gypsy moth (Lymantria dispar). Most of our native species are in two genera: Dasychira and Orgyia.
Similar species: The caterpillars in several moth groups are called “tussock moths” because they, too, may be hairy with clumps of longer hairs. Several of these are in the tiger and lichen moth subfamily.
Wingspan: ½–2¾ inches (varies with species).
Habitat and Conservation
Adult tussock moths are frequently seen around electric lights at night. The caterpillars are associated with their various food plants, so if you are looking for a particular species, find out what its larval hosts are, and seek them out.
Adults lack functional mouthparts and do not eat. Larvae usually eat trees, shrubs, and other woody plants, but some species eat herbaceous plants. Compared to other moth groups, most tussock moths have a rather wide range of acceptable host plants.
The new family (Erebidae) that the tussock moth subfamily now belongs to joins together several additional moth groups. Many of these (such as the underwing, or catocalid moths) used to be members of the formerly huge family Noctuidae. The noctuid family continues, but minus those groups. Another distinct group, the tiger and lichen moths, are in the same situation as the tussock moths: they also used to be in their own family, but have now been reduced to a subfamily (Arctiinae) in the new family Erebidae. These recent taxonomy revisions are confusing, but they represent a much greater clarity in our understanding of the true relationships among these animal groups.
With the females flightless, the males must seek them out, and pheromones (scent signals unique to each species) help the sexes to find one another. Eggs are often laid in a cluster on top of the cocoon and are covered with the female’s irritating hairs.
Several species in this subfamily are destructive agricultural pests. Some species damage shade trees, forest species, or landscaping plants, and others are notorious for chewing the leaves of orchard trees.
People introduced the invasive, destructive gypsy moth to North America in a failed attempt to jumpstart a silk-producing industry on our continent.
Stinging hairs are a defense against the caterpillars’ many predators. The bright colors warn predators of the unpalatable nature of the caterpillars. The hairs also probably help insulate the caterpillars from extreme temperatures and help protect them from drying out.