ENGLISH: ILLINOIS TREES: THEIR INSECT ENEMIES 11 



Pale green or yellow in color, each with a dark stripe down 

 the back and a yellow stripe along each side, the caterpillars do 

 not leave the web until nearly full grown. At this time they 

 move in many directions and feed on almost any green foliage 

 available. When mature, they move to the ground to pupate 

 under sheltering debris or just below the surface of the soil. 



Control Measure 1 or 6 (end of circular). 



BIRCH 



Bronze Birch Borer, Agrilus anxius Gory. — Widely distrib- 

 uted and a serious pest of birch trees in the open, especially 

 white birch, the three-fourths-inch long, white, flattened, and 

 footless grub of this species attacks all parts of the birch above 

 ground, burrowing under the bark and causing the bark to 

 loosen and separate from the wood. The slender bronze beetle 

 that develops from an overwintering grub cuts semicircular 

 holes through the bark and emerges in early spring. The female 

 lays white eggs in bark crevices. Larvae hatching from the eggs 

 penetrate the bark, feed, and grow to develop another genera- 

 tion. 



Control Measure 4- (end of circular). 



Birch Skeletonizer, Bucculatrix canadensis ella Chamb. — 

 Unlike the bronze birch borer, which prefers trees in the open, 

 the larva of this insect prefers woodland trees for its periodic 

 attacks. Tiny caterpillars hatch from eggs placed singly on a 

 leaf by the very small female moth, which is seldom seen. Each 

 caterpillar bores directly into the leaf tissue, mines the leaf for 

 a few weeks, and then skeletonizes the leaf on the under side be- 

 fore dropping to the ground to pupate for the winter. The most 

 extensive damage by this insect is likely to occur in August. 



Control Measure 1 or 2 (end of circular). 



BOXELDER 



Boxelder Bug, Leptocoris trivittatus (Say), fig. 7. — The 

 adult form of this species is a black and red bug that feeds 

 through a long, slender beak on the leaves and seed pods of the 

 boxelder tree. It does little damage to the tree, but it creates a 

 nuisance by congregating in great numbers about the tree and 

 by migrating to nearby dwellings in the fall in search of winter 



