408 ENTOMOLOGICAL NEWS [Nov., '12 



Cremaster attached 10 138 p. m 



Chrysalid still soft 12 :49 a. m. 



Adult emerged August 25, 1902 5 :3O p. m. 



Duration of pupal stage 9 days, 19 hours. 



During the early afternoon of August 15, 1902, as noted 

 above, eight of the larvae were found suspended from small 

 pads of silk spun against one side of a twig of willow. They 

 were fixed and held by the claws or minute hooks of the anal 

 prolegs and during the whole afternoon they remained quietly 

 hanging, the dorsum arched, the head neatly tucked in and the 

 legs passively closed. Between 6 and 8.30 P. M., two chrysa- 

 lids were formed ; at about the same time one of the sus- 

 pended larvae was removed from its position and laid upon a 

 table (3) in following; the other two were closely observed. 

 Three fell to their death as noted already. 



(2) Everything was quiet until 10.30 P. M., August 15, 

 when one of the two suspended caterpillars taken for observa- 

 tion began to move (wriggle) violently as if in agony. A half 

 minute later, the integument parted along the back and the 

 chrysalis commenced to appear, being pushed forward by alter- 

 nating constriction and expansion of the body. At 10.34^2 P. 

 M., after three plus minutes of struggling, all of the body ex- 

 cepting the anal segment had been exposed. The critical stage 

 was now approaching; it occupied more than half of the time 

 of the whole ecdysis. The operation of attaching the cremas- 

 ter of the chrysalis seems simple enough, but is evidently a 

 critical one ; it must be remembered that it is done by instinct, 

 the chrysalis having no previous experience concerning it. 

 The chrysalis has to hold itself by a powerful muscular effort, 

 bending the abdomen in such a manner as to grasp the cast 

 larval skin, then detaching the latter from the anal segment, 

 and then attempt to entangle its cremaster in the silken pad 

 from which the caterpillar had previously suspended itself. 

 After freeing the anal segment, apparently not done without 

 some struggle and seemingly an operation, which, ordinarily 

 would require some practice, the chrysalis has the problem of 

 climbing over the still adhering empty larval integument with 

 nothing to hold on by excepting a very pliable abdomen. 



