202 EXPLANATION OF PLATE. 



weeks; therefore the feeding season in this country lasts about four months. 

 When the caterpillars are first hatched from the eggs they are light in color 

 and covered with whitish hairs. In a few hours they assume a dark hue. 

 They usually remain in or near the egg-cluster until they change in color, and 

 should the weather be cold they sometimes remain for several days in a semi- 

 torpid condition upon the egg-cluster. If the temperature is favorable they 

 usually search for food before they are twenty-four hours old. During the 

 first few weeks of their existence they remain most of the time on the leaves, 

 feeding mainly on the under side. Their feeding habits are so uncertain that 

 no rule can be given which will apply to all individuals, but before they are 

 half grown they generally begin to manifest their gregarious instincts. At 

 that time and for the rest of their existence as caterpillars they spend a large 

 part of the day clustered in sheltered situations, and feed principally at night, 

 going up the trees and out on the branches after dark and returning before 

 daybreak. "Where they are so abundant that the food supply is insufficient 

 they evince much restlessness, and feed in numbers during all hours of the 

 day and night. They may then be seen hastening to and fro, both up and 

 down the trees. Those which have fed sufficiently are at once replaced by 

 hungry new-comers, and the destruction of the foliage goes on incessantly. 



At such times the trunks and lower branches of trees are covered with a 

 moving mass of caterpillars, hurrying throngs are passing and repassing, and 

 nearly every leaf or denuded stem bears up one or more of the feeding insects. 

 The rustling caused by their movements and the continual dropping of excre- 

 ments is plainly audible. On tall trees the larger caterpillars appear to crawl 

 to the higher limbs, and they seem to prefer to feed well out toward the end 

 of the branches. They do not feed gregariously except when in great num- 

 bers ; therefore they seldom strip one branch, as do the larva? of the Vanessa 

 antiopa, but scatter throughout the trees, eating a little from each leaf. 

 Early in the season, when they are small and few in numbers, their ravages 

 are scarcely noticed ; but as they grow larger and more numerous their 

 inroads on the tree decrease the foliage area night by night, until suddenly 

 all the leaves appear to have been eaten in a single night, and the tree is 

 stripped. 



Food Plants. 



The gypsy moth is known to destroy the foliage of nearly all native and 

 introduced trees and plants of economic importance. The list of its food 

 plants includes nearly all evergreen and deciduous trees, most bushes, shrubs, 

 vines and vegetables, and it has been seen to eat grass. Wherever the cater- 

 pillars become numerous they move slowly, devouring nearly every green leaf 

 and bud as they go. They feed during a much longer season than the canker 

 worm or the tent caterpillar. In the months of June, July and August, 1891, 

 trees which had been stripped early in the season and whose leaves had again 

 put out were again defoliated by these caterpillars and kept bare all summer; 

 therefore not only was all prospect of a fruit harvest destroyed, but many 

 trees were killed by this continual defoliation. 



