74 BUTTERFLIES 



organs taking on the forked appearance of a snake*s 

 tongue. 



Obviously it is exceedingly difficult to get definite ob- 

 servations under natural conditions to determine whether 

 these seeming resemblances are really of value to the cater- 

 pillar in frightening away birds or other enemies. About 

 the only direct evidence which I have come across upon 

 this point is found in this paragraph by Dr. J. L. Hancock: 



"When I recall the first sight of this larva, the impres- 

 sion gained of it was a most curious one. The forwg^rd 

 mask-like face was remarkably startling. This mask, 

 bearing eye-like spots and the light transverse ridge, gave 

 it an aspect which might easily be mistaken for real eyes 

 and a mouth. This contrivance is only a false face in no 

 way connected with the real eyes and mouth. One might 

 imagine the shock that a bird, or other predaceous enemy, 

 would experience when looking upon this grinning mask. 

 This is in reality the effect produced, for I have seen small 

 birds so alarmed that they lost their appetite and curiosity 

 for these larvae after a brief glance at them. It is certain 

 that these singular markings have the effect of terrifying 

 their bird enemies."* 



The yearly cycle of the Tiger Swallowtail is much Eke 

 that of the related species. It passes the winter as a 

 chrysahs, the butterflies coming forth just about the time 

 that the lilacs bloom. They remain upon the wing for a 

 few weeks and deposit theu: eggs upon a great variety of 

 trees and shrubs, for the food plants of the larvae are tm- 

 usually varied and include tulip trees, birches, wild cher- 

 ries, apples, poplars, ash, and several other common trees or 



*"Nature Sketches in Temperate America," p. 146. 



