8 ENTOMOLOGICAL NEWS. [Jan., '04 



that the period of susceptibility is brief, and immediately pre- 

 cedes the act of pupation. 



The pupae which I had under observation nearly all showed 

 this phenomenon to a marked degree. The whole number of 

 larvae which pupated successfully on the building and fence 

 was 71. Of these, 29 were on white surfaces, and all formed 

 pupae of a pale ashen color ; 34 were on red surfaces, and 32 

 formed pupae conspicuously marked with brick red ; 8 were on 

 dark surfaces, all formed black or dark gray pupae. 



The exceptional cases were two in the second group, which 

 were black. It is possible that with these individuals the 

 period of susceptibility was reached during the night. 



Of four larvae taken from the building and kept in the labo- 

 ratory, three, which were placed in light-tight wooden boxes, 

 gave black pupae ; and one, which was kept in a white paste- 

 board box covered with glass, gave a pale ashen pupa. 



The three groups of pupae were kept under observation until 

 the butterflies emerged, to see if any significant difference in 

 the duration of the pupal state appeared ; but none was dis- 

 covered. 



CONCLUSION. The larvae of Vanessa antiopa, when about to 

 pupate, react to light, heat, gravity and contact, as summar- 

 ized : 



IviGHT. The larvae give clear evidence of their preference 

 for ordinary daylight over deep shade on the one hand, or the 

 glare of reflected sunlight on the other. The reaction to light 

 is secondary to the heat-reaction until the larva has suspended 

 itself, when the period of greatest susceptibility to light begins. 



HEAT. A certain optimum temperature, apparently not 

 far from 60 F. , encouraged pupation in the most diverse situ- 

 ations. A much lower temperature drove the larvae to shel- 

 tered nooks with southern exposure ; a much higher one sent 

 them into shaded spots. 



GRAVITY AND CONTACT. The responses to gravity are 

 complex and at first somewhat obscure. The larvae crawls 

 down the trunk of the tree and up the front of the building. 

 Favorable conditions of heat and light being found, contact 

 stimuli probably lead it to spin its cushion of silk. Response 



