INSECT ENEMIES OF WESTERN FORESTS 93 



the eggs and destroys a high percentage of them. At least five 

 other wasplike insects are important parasites of the larvae. A 

 virus disease is highly effective in bringing epidemics under 

 control. 



The Douglas-fir tussock moth can be controlled with DDT 

 sprays. In 1947 the outbreak in Idaho and eastern Oregon was 

 brought under control by airplane spraying with 1 pound of DDT 

 in 1 gallon of oil carrier per acre, applied to 413,469 acres — the 

 largest aerial spraying project ever undertaken up to that time, 

 and a highly successful one. 



Other closely related species of tussock moths that feed on forest 

 trees in the Western States are as follows : 



Species of Hemerocampa Host and distribution 



oslari (Barnes) White fir. California and Colorado. 



vetusta (Bdv.) Oak, poplar, willow, and various other broad- 

 leaved trees. Pacific coast. 



gulosa (Hy. Edw.) Oak. California Sierras. 



leucostigma (A. & S.) Poplar and other broadleaved trees. In the east, 



and west into Colorado and British Columbia. 



The rusty tussock moth (Notolophus antiqua (L.)) is a cosmo- 

 politan species which is distributed over much of North America 

 and Europe. It has been recorded in the West from California to 

 British Columbia and east to Montana. The dark, hairy cater- 

 pillars have four dense, white, brushlike tufts of hair on their 

 backs, two black pencils of hairs in front, and one on each side 

 about midway of their bodies; they are V/ 8 inches long when full 

 grown. They feed on alder, ash, aspen, oak, poplar, willow, and 

 other broadleaved trees and shrubs, as well as on various conifers. 



The satin moth (Stilpnotia salicis (L.) ) {19) is a very injurious 

 leaf-eating enemy of poplars and willows. This moth, which is 

 native to Europe, was first reported in 1920, both in New England 

 and British Columbia. Since then the British Columbia introduc- 

 tion has spread throughout western Washington and into Oregon. 

 It is a serious pest of planted shade and roadside trees, and may 

 prove destructive to native poplars and willows. 



The adults are large white moths with a satiny luster, a wing 

 expanse of approximately 1% inches, black eyes and legs, and a 

 tuft of hairs at the tip of the abdomen. The full-grown caterpillars 

 are about 2 inches long, black with white markings on the sides, a 

 row of nearly square white marks along the back, and have brown 

 spines and long hairs. 



There is but one generation a year. During the flight of the 

 moths in July, eggs are laid on trees or other objects in oval 

 patches covered with a white, satiny secretion which glistens in 

 the sun. The young larvae feed for a short time and then spin 

 small cocoons or hibernacula in bark crevices, where they pass the 

 winter. They resume feeding in the spring, and the larvae reach 

 maturity in June, and pupate in loosely woven cocoons attached 

 to leaves or other objects. 



It was introduced without its European parasites, but it is at- 

 tacked by several native enemies, including tachinid flies, parasitic 



