qe MISC. PUBLICATION 273, U. S. DEPT. OF AGRICULTURE 
THE SATIN MOTH 
The satin moth (Stilpnotia salicis L.) (10) 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 introduction 
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 134 inches, black eyes and legs, and a tuft 
of hairs at the tip of the abdomen. The full-grown caterpillars are 
about 2 inches in length, black with white markings on the sides, a 
row of nearly square white marks along the back, and with 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. Feeding 
is resumed in the spring, and the larvae reach maturity in June. 
Pupation occurs 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 
wasps, sarcophagid beetles, mites, and birds. Some of these have 
proved very effective in holding it in check. From 1929 to 1934, 
five species of parasites of European origin were colonized and lib- 
erated in Washington. Four of these have become established and 
at least one, Apanteles solitarius Ratz., has become abundant enough 
to show apparent effect. 
Direct control is obtained by spraying the trees in the spring with 
a stomach poison such as lead arsenate. When egg masses are 
exceptionally abundant they should be treated with creosote. 
TENT CATERPILLARS 
(Mfalacosoma spp.) 
Tent caterpillars (78), which are responsible for the defoliation of 
many different species of trees and shrubs, can be recognized by the 
large compact webs at the terminals of branches, which are such a 
common sight during April and May. ‘The various species are 
indigenous to this continent, being widely distributed over the 
United States. Outbreaks were recorded from Massachusetts as early 
as 1646. Coniferous trees are sometimes attacked, but the preferred 
hosts are deciduous trees and shrubs. While large forest areas are 
sometimes defoliated, the resultant damage is usually of no great 
importance, since deciduous trees can readily recover from the loss 
of foliage. 
The caterpillars that construct the tents are usually yellow to 
brown, with rows of blue or orange spots and lines, and are lightly 
covered with long hairs. A heavy, silk-lined cocoon is usually formed 
in bark crevices or in leaves webbed together. The adults are tawny 
yellow or brown moths or millers and are frequently seen flying about 
lights at night. 
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