44 



remained together during the greater part of the day. When 

 about to molt their usual places for congregating are upon the 

 branches and trunks of the infested trees. The young caterpil- 

 lars are more often found upon the former and those that are near- 

 ing full growth upon the latter or on the large limbs of the larger 

 trees. Plates IV is from a photograph of a group of caterpillars, 

 most of which were not more than half grown, upon a limb of a 

 young basswood tree. This photograph was taken at 1 1 :30 a.m. 

 In the sections of the State where the caterpillars were very 

 abundant they were frequently found together, when preparing to 

 molt, in such large numbers as to completely cover one side of 

 the trunk of a full-grown sugar maple tree to the distance of three 

 or four feet. Plate V is from a photograph taken at 3:15 p.m., 

 of a comparatively small group of caterpillars about two-thirds 

 grown upon a small plum tree in an orchard near Geneva. 



Restlessness of the full-grown caterpillars. — After the last molt the 

 caterpillars become very restless, wandering up and down the 

 trunks, along fences, etc, until finally the cocoons are spun. It 

 has been observed that they feed but little during this period. 

 This was also indicated by the colonies kept in our breeding cages. 

 After the last molt they ate but very little, wandering about for 

 three or four days and finally spinning their cocoons in all parts 

 of the cages. 



Number of molts and descriptions. — The number of molts is 

 usually four. A fifth molt occurs soon after the cocoon is spun. 

 The molting periods, with the exception of the first, which was 

 not observed, of a large number of caterpillars confined in breed- 

 ing cages last spring were as follows : The first molt was about 

 May 8, the second May 16, the third May 31. About ten days 

 later part of them molted a fourth time and within three days 

 spun their cocoons. A small proportion of those that molted but 

 three times spun cocoons. The remainder died. This lack of 

 normal development was probably due to insufficient food as they 

 were accidentally deprived of fresh food for nearly two days between 

 the third and fourth molts. The periods of molting and the 

 markings were observed and recorded by C. V. Riley'' in 1870. 

 The following descriptions do not difier essentially from those 



"Amer. Ent. and Bot., 28 262. 



