38 OUR SHADE TREES AND THEIR INSECT DEFOLIATORS. 
The Larva (Fig. 18, a, b, and c).—“ The caterpillars just born 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, 
Fic. 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; f, 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. 
