LARCH SAW-FLY 



285 



with tree tanglefoot in September prevents the wingless females 

 from climbing the trees. 



The Elm Leaf Aphis. This is the very common louse (Schi- 

 zoneura americana Riley) found in clusters on the under side of 

 the leaves of the elm, where it may be seen covered with a whitish 

 powder and exuding " honey dew" which attracts ants. 



Injury. Its attack causes the leaves to curl, forming more or 

 less of a gall. If the louse appears in large numbers, the leaves 

 at the tips of twigs turn yellow, rendering the trees very unsightly. 



Life History. Eggs are laid in the fall in cracks and crevices 

 of the bark. The young hatch in the spring and crawl to the ter- 



FIG. 2S8. The larch saw fly; below, caterpillar, after Ruggles; above, male saw fly. 



minal twigs. The life history, in a general way, corresponds to 

 that of other plant lice. 



Control. At the first appearance of lice in the spring, infested 

 twigs should be cut off and burned, thus preventing the many 

 summer broods. 



The Larch Saw-Fly. This saw-fly (Lygaconenatus erichsonii 

 Hart) is one-half an inch long, with a blackish body and a red 

 band across the middle of the abdomen (Fig. 288). The larva is 

 a pale-green worm of about the same length. 



Injury. It feeds upon our tamaracks, hemlocks, and larches. 

 This insect is one of the most injurious forms found working on 

 shade trees. It defoliates vast areas, killing the trees and causing 



