362 INSECTS INJURIOUS TO VEGETATION. 



general color of the body ; the belly is paler. When not eat- 

 ing, they remain stretched out at full length, and resting on 

 their fore and hind legs, beneath the leaves. When fully 

 grown and well fed, they measure nearly or quite one inch in 

 length. They leave off eating when about four weeks old,* 

 and begin to quit the trees ; some creep down by the trunk, 

 but great numbers let themselves down by their threads from 

 the branches, their instincts prompting them to get to the 

 ground by the most direct and easiest course. When thus 

 descending, and suspended in great numbers under the limbs 

 of trees overhanging the road, they are often swept off by pass- 

 ing carriages, and are thus conveyed to other places. After 

 reaching the ground, they immediately burrow in the earth, to 

 the depth of from two to six inches, unless prevented by weak- 

 ness or the nature of the soil. In the latter case, they die, or 

 undergo their transformations on the surface. In the former, 

 they make little cavities or cells in the ground, by turning 

 round repeatedly and fastening the loose grains of earth about 

 them with a few silken threads. Within twenty-four hours 

 afterwards, they are changed to chrysalids in their cells. The 

 chrysalis is of a light brown color, and varies in size according 

 to the sex of the insect contained in it ; that of the female 

 being the largest, and being destitute of a covering for wings, 

 which is found in the chrysalis of the males. The occurrence 

 of mild weather after a severe frost stimulates some of these 

 insects to burst their chrysalis skins and come forth in the per- 

 fected state ; and this last transformation, as before stated, 

 may take place in the autumn, or in the course of the winter, 

 as well as in the spring ; it is also retarded, in some individ- 

 uals, for a year or more beyond the usual time. They come 

 out of the ground mostly in the night, when they may be seen 

 struggling through the grass as far as the limbs extend from 

 the body of the trees under which they had been buried. As 

 the females are destitute of wings, they are not able to wander 



* In the year 1841, the red currant flowered, and the canker-worms appeared, 

 on the fifteenth of May. The insects were very abundant on the fifteenth of 

 June, and on the seventeenth scarcely one was to be seen. 



