8 
Later they can readily be collected singly by hand from trees of 
small size, or they may be poisoned, like most of the leaf feeders, 
by spraying with arsenicals when they are active on the tree. 
The Walnut Caterpillar 
(Datana intcgcrriina G. & R.) 
The most annoying insect enemy of the walnut is a blackish^ 
somewhat striped, hairy caterpillar (Fig. 6), an inch and a half 
long when full grown, which eats the leaves during the latter part 
of the summer, often largely denuding the tree. It makes itself 
particularly offensive on lawns by dropping quantities of refuse 
from the tree and by crawling over walks and buildings when it 
comes down to go into the ground. 
This caterpillar is readily distinguished by its loose coat of 
soft whitish hairs, and particularly by its habit of raising both ends 
of the body when at rest and throwing itself into this position and 
jerking sidewise when disturbed. It often attracts attention by col- 
lecting in masses upon the larger branches or the trunk of the tree 
preliminary to molting, piling up in this way two or three layers 
deep. When full grown it comes down the trunk to the ground, 
wanders about to a short distance and enters the earth an inch or 
two, changing there to a reddish-brown or blackish-brown chrysalis 
(Fig. 6, B). In this stage it winters, emerging the following sum- 
mer, mainly in June and Jul}-, in the form of a buff-brown moth 
(Fig. 6, A) with darker bands across the fore wings. The females 
lay their eggs in clusters varying from seventy-five to a hundred, 
according to some observers, and from five hundred to twelve 
hundred, according to others, and the young hatching from these 
feed in dense clusters, completely devouring every leaf as they go. 
When all the leaves on one twig or branch are destroyed, they mi- 
grate to another, sometimes in a -distant part of the tree. They 
lose their gregarious habit as they mature, and by the time they are 
full grown they scatter here and there over the greater part of 
the tree. There is but a single generation in a year. 
Altho they are most frequently seen on the walnut, they are 
common on butternuts and hickories, and are a pest to the grower 
of the pecan. They have likewise been found on beech, oak, willow, 
honey-locust, apple, and thorn. Trees in the forest are not likely 
to suffer, but those on streets and lawns are sometimes so completely 
stripped by September that they stand almost as naked as in mid- 
winter, only the green nuts remaining on the branches. 
This account of their habits is sufficient to suggest various avail- 
able methods of destroying them. On trees small enough to be 
reached they can be readily killed while young by clipping off the 
