SHADE TREE INSECTS 



25 



The caterpillars prefer the foliage of poplar, aspen, and willow, and most of 

 the injury is confined to these hosts, entire trees and groups of trees having been 

 defoliated. 



Description. The moths of both sexes are entirely white with a satiny luster. 

 The female has a wingspread of about 2 inches. The male is slightly smaller. 



The individual eggs are minute, round, and slightly flattened. They are pale 

 green when first laid but gradually turn brown. They are laid in one or two 

 la\crs in flat, oval masses about }/2 inch wide and 3/5 inch long, and are covered 

 with a white secretion that glistens in the sun. A single mass may contain 100 

 to 300 or more eggs. 



The full-grown caterpillars are about 1 V2 to 2 inches long. The head is black. 

 The body is black with fine white markings. Along the back is a series of large 

 whitish blotches var^^ing from almost square to dumbbell shape. Along each 

 side arc two thin, broken, whitish lines. On each body segment there is a trans- 

 verse row of brown tubercles each bearing a tuft of long hairs. 



The pupa is almost 1 inch long. It is shining black and covered with tufts of 

 long whitish to golden hairs on all but the ventral surface. The cocoon is loosely 

 made of silken threads and attaches the pupa, which is easily seen through the 

 cocoon, to a leaf, twig or other object. 



Satin Moth 



1. Injured poplar leaf. 



2. Adult female moth. Actual size. 



3. Caterpillar. Actual size. 



Figs. 1 and 2, Courtesy, Bur. Ent. and Plant Quarantine, U. S. Dept Agr. 



Life History. Partially grown caterpillars (third stage) pass the winter under 

 a small, firm web which is usually constructed in crevices of the bark or in other 

 protected places. From late April through May they emerge from hibernation 

 and feed on the foliage. They molt seven times as the\' mature and finally become 

 full grown the latter part of June. They then pupate in loosely made cocoons 



