SHADE TREE INSECTS 



65 



attack the succulent bark near the tips of the basket willow shoots, causing them 

 to branch and thus become unfit for basket making. 



Two closely related species also attack the foliage of poplar and willow in some 

 parts of the country. They are Chrysomela lapponica Linn., and C. tremulae 

 Fabr. 



Description. The beetles of C. scripta vary in length from about }4, to 1/3 

 inch. They are oblong-oval in shape. The markings on the beetles vary consid- 

 erably. The head and thorax are black, the latter having broad lateral margins 

 oi brick red. The wing covers are >-ellow to golden, and on each are three more or 

 less interrupted black lines which vary in size and extent so that in some beetles 

 the gold predominates and in others the black. The side and hind margins are 

 brick red. 



The eggs are laid side by side in groups, usually on the under side of a leaf and 

 fastened to it in a slightly slanting position. Twenty-five or more may be found 

 in a single cluster. They are lemon yellow in color turning to a deep salmon just 

 before hatching, elongate-oval in outline, and approximately 1/30 inch long. 

 The shell is smooth, thick, and leathery. 



The larva, or grub, is about 3/8 inch long. The body is a dirty-yellowish color, 

 the head a dark brown, and the legs black. A double row of dark brown spots, 

 two on each segment, extends along the upper surface of the abdomen. In line 

 with these, on each side, is a row of black tubercles which, when the insect is 

 disturbed, emit drops of a white, milky fluid which has a pungent odor. At the 

 tip of the abdomen there is a disk covered with a sticky substance which is used 

 as an aid in crawling about. When ready to pupate, the grub attaches itself to 

 the under side of a leaf with this disk and hangs head downward. The pupae, or 

 "hangers", are about 1/3 inch long. 



Cottonwood Leaf Beetle, Chrysomela scripta 



Adult beetle (left), egg mass (lower right), and grub (upper right). Greatly enlarged. 

 Courtesy, N. J. Agr. Expt. Station. 



Life History. The beetles spend the winter in sheltered places such as under 

 logs or loose bark, in crevices in fence rails, or beneath debris on the ground. 

 About the time the leaves develop, the beetles begin to feed on the leaves and 

 tender bark of the young shoots, preferring the latter. In a few days the adults 

 begin to lay their lemon-yellow eggs in groups, usually on the under side of the 

 leaves. The egg-laying period lasts a week or more. Tiny, dark grubs usually 

 appear in about 2 weeks and proceed at once to skeletonize the lower leaf surfaces. 



