proportion of favored host species also decreases the chance of infestation and 
limits the degree of population buildup (4). 
Insecticidal spraying by aircraft has been used widely in gypsy moth control. 
Various chemical insecticides are effective. Attempts to secure control by spraying 
infested stands with the nuclear-polyhedrosis virus continue with some success 
(733, 989, 1033). Spraying with the microbial insecticide, Bacillus thuringiensis 
Berliner (25, 343), has given foliage protection. Another possible method of 
control is the use of synthetic sex attractants. The natural female attractant has been 
isolated, identified, and synthesized (/06, 626); the synthetic pheromone is known 
as disparlure. It has been particularly useful in survey and detection work (/072). 
The use of the sterile-male technique for controlling gypsy moth continues to be 
investigated (827, 1073). 
The satin moth, Leucoma salicis (L.) (fig. 102), an introduced species first 
discovered in North America near Boston, Mass., in 1920 and in British Columbia 
during the same year, now occurs throughout most of New England and in the 
Maritime Provinces of eastern North America. In the West, it has spread southward 
through western Washington into northwestern Oregon. The larvae feed on most 
species of poplar and willow. Adults of both sexes are pure white with a satiny sheen 
and have a wingspread of 37 to 50 mm. The head, thorax, and abdomen are black 
but are so densely clothed with long, satiny-white hairs they appear white. Full- 
grown larvae are about 34 mm long. The head is black with a bluish tinge. The 
body is blackish on top with a row of large white blotches down the middle and a 
narrow broken line along each side. There 1s also a transverse row of reddish-brown 
tubercles on the top of each body segment, each bearing a tuft of yellowish-brown 
hairs. 
Winter is spent in the larval stage. Feeding is resumed in April in New England. 
Young larvae feed only on the leaf surface, most often on the underside. Partly 
grown larvae eat small, irregular holes in the leaf, and full-grown larvae devour the 
entire leaf except the large veins. Feeding is completed by June. Pupation occurs in 
loosely woven cocoons of silk spun in the leaves or on twigs or other objects. Adults 
appear in late June and early July. Eggs are deposited on leaves, branches, and 
trunks of trees or on other surfaces in masses of 100 to 400. Each mass is oval, 
about 9 mm long, and covered with a glistening white secretion. Hatching occurs in 
about 2 weeks. Newly hatched larvae feed for 5 to 6 days and then spin small webs 
in which they molt to the second instar. These larvae then feed again for 5 to 6 days. 
Then they crawl to limbs or the trunk and spin hibernacula in bark crevices or under 
loose bark where they remain until the following spring (/74). 
The satin moth is not very important as a forest insect in the Eastern States, 
although heavy infestations are occasionally reported. From time to time, it se- 
riously defoliates poplars in ornamental plantings. A number of natural enemies 
(dipterous and hymenopterous parasites, fungi, insect and vertebrate predators) 
cause mortality of eggs, larvae, pupae, and adults (328, /236). 
The browntail moth, Euproctis chrysorrhoea (L.) (fig. 103), an introduced 
species, was first recorded in North America in Somerville, Mass., in 1897. During 
the next few years, it increased enormously and spread rapidly. By 1905, it was 
extremely abundant throughout Rhode Island, eastern Massachusetts, southern 
New Hampshire, and southwestern Maine, and had been recorded as far north as 
New Brunswick and Nova Scotia. Ten years later, most of the area east of the 
Connecticut River, with the exception of northern New Hampshire and Maine, was 
heavily infested. Infestations also occurred in Vermont and west of the Connecticut 
239 
