296 INSECTS AFFECTING VEGETATION 



They feed upon the undersides of the leaves, leaving the vein work 

 and epidermis above. Soon the injured portions of the leaf die. 



The grubs become full grown in from 2 to 3 weeks, or possibly 

 longer, depending upon the weather conditions. At the conclusion 

 of larval development the insects crawl about and either pupate in 

 the crevices of the bark or in some nearby shelter. Often they may 

 be seen lying helpless in considerable quantities at the base of the 

 tree. It is quite likely that only two generations occur annually. 

 Elms only are attacked. 



The Cottonwood Leaf-Beetle. Young Carolina poplars grow- 

 ing in nurseries in Kentucky are often badly damaged by the 

 gnawing of an insect much like the willow leaf-beetle described 

 below in size and general character, but it appears to prefer poplars 

 to willows, though sometimes found also on willow. Both insects 

 occur throughout the central states, but the one now under con- 

 sideration appears to be the more eastern in distribution. 



This beetle measures from about 0.28 to 0.34 inch in length. 

 It is brown, with black head, the thorax brown at the sides and with 

 a black isolated dot in this area on each side, the disc black as in the 

 related insect. The wing covers are notably different from those 

 of the other beetle, being here marked with short lines and dots, in- 

 stead of with dots alone, of black. These dots and lines occupy 

 much the same position, however, as the dots on the wing covers of 

 the willow leaf-beetle, two dots being near the base, two lines near 

 the middle, and the remaining pair, consisting of a line and a dot, 

 placed near the tip and with the line joining a narrow black sutural 

 edging. Beneath, the body is black, w T ith the bases of the femora 

 and the middle region of the tibiae red. 



Both species do their mischief here early in the season, and 

 then disappear from the nurseries. Whether or not other broods 

 develop during the season in other situations has not been deter- 

 mined. As in the other species, the adults hibernate among dead 

 leaves, grass and rubbish. 



The same treatment is to be employed as for the willow leaf- 

 beetle, namely, spraying the attacked foliage with Paris green or 

 arsenate of lead in water. (Bui. 120 Ky. Agr. Exp. Sta.) 



The Vagabond Gall-Louse. The peculiar growth described 

 below as appearing on willows as the result of attacks of mites has 

 not been observed on poplars, but a somewhat similar, though rather 

 more symmetrical growth, is often seen in winter at the tips of twigs 

 of the latter. It looks at first glance like a dried up leaf, but stands 

 perfectly rigid. This growth is found on examination to be a flat- 

 lobed gall that has grown on the twigs during the summer as a 

 result of the attack of a plant louse that lives within. In winter 

 the galls are blackish, and measure an inch or more across. The 

 insect is shining, black, soft-bodied, with delicate membranous 

 whitish wings expanding about one-half inch. It belongs to a gall- 

 producing group of plant lice, distinctly related with familiar 

 species such as the rose aphis and corn plant louse. When it leaves 

 the gall it wanders in an apparently aimless fashion, being found 



