Family Lymantriidae 
Tussock Moths 
This family includes some of the insects that most seriously defoliate trees in the 
United States. The female moths of certain species are wingless; others, though 
winged, are so heavy-bodied that they are either unable to fly, or can fly for only 
short distances. The remainder are strong fliers. The females of some species pack 
and cover their eggs with their abdominal hairs; others coat their eggs with a viscid 
secretion that hardens and forms a protective covering. The urticating hairs of 
certain species in all stages may cause allergic reactions in people when they come 
in contact with skin. The larvae of our native species also bear conspicuous tufts of 
hairs on top of certain body segments. 
The rusty tussock moth, Orgyia antiqua (L.), occurs throughout southern 
Canada and in the northern part of the United States. Its hosts include scores of 
species of both deciduous and coniferous trees (404). The male adult is rusty 
colored. The forewings are crossed by two darker bands and each bears a conspic- 
uous white spot near the border. Females are gray and wingless. Full-grown larvae 
are about 28 mm long and have black heads and dark-gray bodies. The second 
abdominal segment bears a black hair pencil on each side, and there are reddish- 
orange tubercles bearing hairs. The tufts on the prothorax and abdomen are similar 
to those on the larvae of the whitemarked tussock moth. The female deposits her 
eggs in a single-layered, naked mass on the cocoon from which she emerges. There 
are one and possibly two generations per year. This species is sometimes abundant 
locally. Conspicuous defoliation has been recorded in Canada. 
The whitemarked tussock moth, O. leucostigma (J. E. Smith), occurs com- 
monly throughout the Eastern United States and eastern Canada and feeds on a 
wide variety of deciduous and coniferous trees. Preferred species appear to include 
the following: apple, basswood, elm, and poplar; Norway, silver, and planetree 
maples; sycamore; paper and yellow birches; larch; and balsam fir. The female adult 
is wingless, grayish to light brown, hairy, and about 12 mm long. Males are ashy 
gray, and have fully developed wings with a wingspread of about 30 mm. The 
forewing has a conspicuous white spot near the anal angle, and is marked with dark 
wavy bands. Full-grown larvae (fig. 100) have coral-red heads and thoracic shields, 
yellow to cream-colored bodies, and are about 25 to 37 mm long. There is a pair of 
upright pencils of black hairs on the prothorax and another black tuft on the eighth 
abdominal segment. There are also brushlike tufts of white or yellowish hairs on 
each of the first four abdominal segments and reddish dots on the sixth and seventh 
segments. The sides of the body are clothed in white and blackish hairs radiating 
from rows of small yellow tubercles. 
Winter is spent in the egg stage and hatching occurs between April and June. 
Young larvae feed on the surface of the leaves, skeletonizing them. Later, they chew 
holes in other leaves and finally consume all but the larger veins. Young larvae 
often spin down on silken threads and are sometimes transported considerable 
distances by the wind. The larvae become full grown in 5 or 6 weeks, then, under 
branches or in bark crevices, they spin grayish cocoons consisting of silk and hairs 
from their bodies. The pupal stage lasts about 2 weeks. Usually there are two 
generations per year. 
The whitemarked tussock moth may be a pest of shade trees in cities and towns. 
It also occurs in forested areas but usually causes minor damage there. The life 
history, habits, and parasites of the species are discussed (404, 609). 
DoT 
