38 



OUR SHADE TREES AND THEIR INSECT DEFOLIATORS. 



The Larva (Fig. 18, a, b, and e). — "The caterpillars just boru are pale 

 yellow, with two rows of black marks along the body, a black head, and 

 with quite sparse hairs. When full grown they generally appear pale 

 yellowish or greenish, with a broad dusky stripe along the back and 

 a yellow stripe along the sides; they are covered with whitish hairs, 

 which spring from black and orange-yellow warts. The caterpillar is,. 



4i§ 



% 



Wi 



/ 





# 



Fig. 18.— Hyphantria cunea: a, dark larva, seen from side; 6, light larva from above; c, dark larva 

 from above; d, pupa from below; e, pupa from side; /, moth. 



however, very variable both as to depth of coloring and as to mark- 

 ings. Close observations have failed to show that different food pro- 

 duces changes in the coloration ; in tact, nearly all the various color 

 varieties may be found upon the same tree. The fall generation is, 

 however, on the whole, darker with browner hairs than the spring gen- 

 eration. 



"As soon as the young caterpillars hatch they immediately go to work 

 to spin a small silken web for themselves, which by their united efforts 

 soon grows large enough to be noticed upon the trees. Under this pro- 

 tecting shelter they feed in company, at first devouring only the green 

 upper portions of the leaf and leaving the veins and lower skin unmo- 

 lested. As they increase in size they enlarge their web by connecting- 

 it with the adjoining leaves and twigs; thus as they gradually work 

 downwards their web becomes quite bulky, and, as it is filled with 

 brown and skeletonized leaves and other discolored matter, as well 

 as with their old skins, it becomes quite an unpleasant feature in 

 our public thoroughfares and parks. The caterpillars always feed 

 underneath these webs ; but as soon as they approach maturity, 

 which requires about one month, they commence to scatter about, 

 searching for suitable places in which to spin their cocoons. If very 

 numerous upon the same tree the food-supply gives out, and they 

 are forced by hunger to leave their sheltering homes before the usual 

 time. 



