16 PROCEEDINGS OF THE NATIONAL, MUSEUM vou 71 



curled around so that its edges overlapped for half an inch or more, 

 forming a cylinder which had been lined with silk and the ends of 

 which had been closed with silk. 



Pupa. — We have searched very carefully for the pupa of this 

 species, but we have never been able to find a single one, though we 

 have found many caterpillars suspended from silken buttons pre- 

 paratory to pupation. These were mostly on dead cat-tail leaves, 

 dead leaves and stems of grasses, and dead stems of asters and other 

 herbaceous plants. 



We believe that the pupae of this butterfly after becoming hard- 

 ened normally drop from their supports and lie upon the ground 

 until the butterflies emerge. The pupae are weakly attached to the 

 button, and the caterpillars are singularly careless in regard to the 

 supports chosen for pupation. Caterpillars pulled from the button 

 and forced to pupate lying on their side form pupae just as perfect as 

 those which are formed suspended. 



The duration of the pupal stage was 10 days for both sexes. A 

 number of female caterpillars which were kept in an incubator at 80° 

 for 4 da3'^s beginning just after suspension emerged in 7 days. Others 

 which were placed on ice emerged in 10 days plus the length of time 

 they were on the ice, whatever that was. 



Exposure to heat. — Twenty-four female caterpillars ready for 

 pupation were kept in an mcubator at a constant temperature of 

 80° for 4 days. All the pupae formed in the incubator transformed 

 to butterflies. The length of the pupal life was shortened to 7 days 

 from the usual 10. 



All the butterflies were perfect and showed no deviation from the 

 normal except that in three the white spots on the upper surface 

 were slightly enlarged and the two outer rows on the primaries tended 

 to become confluent (pi. 5, figs. 34, 35, 38, 39). 



Exposure to cold. — Twenty-four female caterpillars ready for pupa- 

 tion were kept at a temperature of 40° for var^^^ing periods of time. 

 All the pupae formed transformed to butterflies. The pupal life was 

 in all cases lengthened to 10 days plus the length of time spent in 

 the cold chamber. 



About one-quarter of the butterflies had one or more of the wings 

 reduced in size, but there were no other deviations from the normal 

 (pi. 5, figs. 33, 36). 



Parasites. — On March 1 a single parasitic larva emerged from one 

 of the caterpillars brought to Washington from Essex, Massachusetts, 

 and formed a cocoon about half an inch away from its victim. This 

 parasite was identified as Apanteles clisiocampae by Mr. R. A. 

 Cushman. 



