Browntail moth is a serious pest on fruit trees and shade trees in New England. The moth has a wingspread of about 11/2 inches (3.8 centimeters). It is pure white with a brown abdomen. Both adult and caterpillar browntail moths have threadlike structures called hairs. These structures are not true hairs, which grow only on mammals, but they resemble true hairs. Adult browntail moths fly well.
The female lays about 300 eggs in July. Caterpillars emerge from the eggs after two to three weeks and begin to eat. When small, they do much damage by eating leaves. In autumn, when only partly grown, the caterpillars spin small, tough tents of silk at the tips of twigs. They spend the winter in these tents. In spring, they emerge and begin eating again.
When fully grown, the caterpillars spin loose cocoons and change into pupae. They develop into adult moths by July. The caterpillars are brown, mixed with orange to whitish, and have two bright spots on their backs. Many of their hairs, as well as some hairs of the female moths, irritate human skin and cause a rash. Because the wind may blow great quantities of the hairs about, they can be a serious problem.
The number of browntail moths has decreased as a result of control measures by people, the attacks of parasites, and cold winter weather. The insects can be destroyed by removing and burning the tents in winter. Other control measures are the same as for the spongy moth (see Spongy moth).
See also Caterpillar; Moth; Tussock moth.
