372 S. J. HOLMES AND K. W. McGRAW ■ 



right side to the light. Almost immediately the butterfly at- 

 tempted to. turn toward the light, and by the action of its legs 

 caused the disk to rotate in the opposite direction. After a 

 few rotations of the wheel the butterfly was turned into the 

 reverse position so that its left side was exposed to the light. 

 Within a few seconds it began to turn the disk away from the 

 light as before. When replaced in its original position the but- 

 terfly rotated the disk again toward the left side. Several sub- 

 sequent trials gave similar results, and another specimen of the 

 same species responded in practically the same way as the one 

 described. 



Experiments with M elites a chalcedon gave results very similar 

 to those with the cabbage butterfly. When the insect was held 

 pointing obliquely away from the light it would still turn the 

 disk away from the more illuminated side. When pointing 

 obliquely toward the light the butterfly would give the same 

 response. In every position except that in which the body was 

 parallel to the rays there were efforts to turn toward the light 

 which resulted in the rotation of the disk. If the insect was held 

 facing the light and parallel to and near one edge of the disk, 

 rotary movements were set up as _ a consequence of attempts 

 at forward locomotion. In many cases the disk would be rotated 

 for several minutes without cessation, and when the butterfly 

 became quiet it could generally be caused to resume its activity 

 by pulling it slightly backwards. In both Pieris and Melitsea 

 the head was kept turned slightly toward the light. Eurymus 

 eurytheme and Cosnonympha californica also rotated the disk 

 away from the light. Most of the specimens of Euvanessa 

 antiopa experimented with failed to give results on account of 

 feigning death so long as they were held, but one individual 

 became active after a time and consistently rotated the disk 

 away from the illuminated side. 



Two species of Diptera of the family Tachinidae rotated the 

 disk uniformly away from the light. Other species when held 

 would execute only irregular movements. The same was true 

 of several other phototactic insects belonging to different orders. 

 The aculeate Hymenoptera expended most of their energy in 

 efforts to sting their captor, and attempts to escape in most 

 other cases effectually overcame any phototactic proclivity that 

 may have existed. However, the comparatively few insects 



