No. 4.] THE GYPSY MOTH. 271 



its food plants includes nearly all evergreen and deciduous trees, most 

 bushes, shrubs, vines and vegetables, and when hard pressed it has been 

 seen to eat grass. \ATierever the caterpillars become numerous they 

 move slowly, devouring nearly every green leaf and twig as they go. 

 Some of their favorite food plants are the apples, willows, elms, oaks, 

 Norway spruce, rose, strawberry and wistaria. They feed during a 

 much longer season than the canker worm or the tent caterpillar. The 

 eggs of the gypsy moth begin hatching about April 20, and the young 

 continue to emerge until the middle of June. 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. Not only was all jjrospect of 

 a fruit harvest destroyed, but the life of the trees was threatened by 

 such constant defoliation. 



History of the Work. 



The field work of the season of 1891 consisted largely of organi- 

 zation, experiment, inspection and observation. An attempt was made 

 to define the boundaries of the infested region. The territory was 

 mapped, divided and subdivided ; the force of men was mobilized to 

 keep pace as far as possible with the discovery of badly infested locali- 

 ties, and labor was concentrated upon those districts where the moth 

 appeared in greatest numbers. The habits of the moth and those of its 

 parasites and enemies were observed and recorded ; its distribution was 

 studied, and a series of experiments with insecticides was conducted. 

 This work, together with that of destroying the several forms of the 

 moth, occupied the entire season, and it was not mitil January, 1892, 

 that the bomidaries of the district occupied by the moth could be even 

 approximately given. The appropriation of 1891 proved insufficient to 

 maintain such a force as was needed to attain the best possible results ; 

 therefore, on the first of January, 1892, but forty men were retained in 

 the field. This force was at that time concentrated in the region most 

 densely infested, and was there emplo^-ed in cutting and burning worth- 

 less infested trees and shrubbery, and in destroying eggs by this and 

 other methods until the snow disappeared. 



•■ In the spring and fall of 1891 the egg clusters were cut or scrajjed 

 from the objects to which they were attached, and burned. This method 

 proved to be somewhat ineffective, as eggs were thus occasionally scat- 

 tered and lost. During the winter of 1891-92 experiments were made to 

 test the eff"ect of cold, rain, snow and ice upon scattered eggs. Twelve 

 thousand eggs were exposed during most of the winter to changes of 



