HATCHING OF THE EGGS. 297 



that such hatching had actually taken place in the infested 

 district. In the light of our present knowledge, however, 

 it seems probable that fall hatching may have occurred occa- 

 sionally during previous years, and also that, under the most 

 favorable conditions, this insect shows a tendency to be- 

 come double-brooded, like the related species of the genus 

 Orgyia, 



The death of the caterpillars of the second brood, feeding 

 in the field, was to be expected, since the season was not long 

 enough to permit them to reach maturity. Even if they had 

 matured it is doubtful if the caterpillars would have seriously 

 injured trees which had retained their foliage throughout the 

 summer. 



On the softer and more delicate foliage of those trees 

 which had leaved out a second time, after being stripped 

 early in the season, the caterpillars fed with great avidity, 

 and, had the length of the season permitted, such trees might 

 have been injured to a considerable degree. 



HATCHING OF THE EGGS. 



The majority of the eggs hatch during the warm part of 

 the day, from 10 A.M. to 2 P.M., and continue hatching for 

 several days. It is apparent that, when hatching, the cater- 

 pillar first eats a hole through the side of the egg-shell, the 

 flattened surfaces representing the top and bottom of the 

 egg, and then eats more or less of a band around the shell 

 on the side, often leaving only the upper and lower surfaces 

 of the egg. Sometimes the caterpillar emerges from the 

 egg by a single hole in the side, but usually it eats a band 

 around the side of the egg, leaving only the upper and lower 

 disks remaining. 



NUMBER OF CATERPILLARS FROM SINGLE EGG-CLUSTERS, 

 AND TlME REQUIRED FOR HATCHING. 



From one egg-cluster that had been kept in a warm room at 

 the insectary during the winter of 1893-94, 1 egg had hatched 

 Feb. 23, 1894, at 9 A.M. ; at 10 A.M., 49 more; at 11 A.M., 

 13 more ; and at 5 P.M., 50 more, making 113 which hatched 

 the first day. 



