18 NEW YORK STATE MUSEUM 



giving an idea of what a drain this species must be on a tree's 

 vitality. The limbs which have harbored the bark louse for a 

 few years begin to die, the tree itself shows signs of weakness,. 

 and when it is attacked by both the elm leaf beetle and the 

 bark louse, its destruction follows in a few years. 



Description and life history. The adult females are rather 

 conspicuous during April, May and June. They may be found 

 on the under sides of the smaller branches, frequenth^ clustered 

 in masses and appearing not unlike certain lichens. Each at 

 this time is about ro inch long, oval in outline, with the extremi- 

 ties slightly pointed, and if crushed causes a reddish stain from 

 the contained ova. The body is surrounded by a mass of white, 

 woolly secretion and the segmentation is also indicated by the 

 same substance, as shown in pi. 8, fig. 1. The minute yellow 

 young make their appearance early in July and soon settle for a 

 time on the greener twigs and along the principal veins of the 

 leaves. Occasionally a greenish twig will be almost yellow on 

 account of the large number of young settled on it. In the 

 autumn the back of the partly grown bark louse is covered with 

 spiny processes which excrete a protective, whitish waxy matter. 

 Most of the insects forsake the leaves at this time and settle for 

 the winter in crevices of the bark. The females molt for the last 

 time early in April, and the males spin their oval cocoons (pi. 8,^ 

 fig. 2). The delicate, four winged reddish male is rarely seen, 

 though of particular interest from its presenting a partially 

 developed form known as the pseudimago. The latter was 

 present in large numbers May 10, 1900, while the perfect males 

 were not found till the 21st. 



Means of distribution. As the slender males onlv are winged^ 

 the insect is dependent largely on various outside agencies for 

 its distribution. It has most probably been carried to Nevada, 

 California and other distant localities on infested nursery stock, 

 but this does not explain its general occurrence in such cities 

 as Albany and Troy. Its distribution in these two places, at 

 least, appears to have been largely effected by the aid of the 

 English sparrow and other birds; the active young can easily 



