62 BUTTERFLIES 



cast off the chrysalis takes on a brownish color which as is 

 so often the case is likely to vary somewhat according to 

 the tint of the surrounding surfaces. This is doubtless a 

 protective device and helps the insect to escape attack by 

 birds during the long period of exposure. For this butter- 

 fly passes through the winter only in the chrysahs con- 

 dition, and the larva which went into the chrysalis in 

 September does not come out as a butterfly until the fol- 

 lowing May or June. There are, however, two broods of 

 the butterflies in the North and at least three in the South. 

 As the adults live for about two months and there is con- 

 siderable variation in the periods of their development it 

 happens that one can find these Black Swallowtail butter- 

 flies upon the wing almost any time in warm weather, 

 either North or South. 



The Giant Swallowtail 



Papilio thoas 



The largest of our North American butterflies is a mag- 

 nificent insect with a wing expanse of some four inches and 

 with a rich coloring of black and yellow more or less suf- 

 fused with greenish or bluish iridescence that gives it a 

 striking beauty as it flies leisurely about from flower to 

 flower or stops to lay an egg upon some bush or tree. The 

 tails are long and expanded toward the tip, their prevailing 

 color being black with a broad splash of yellow near the 

 end. In a general way we may say that the upper wing 

 surface is black marked with two bands of orange-yellow, 

 while the under surface is yellow marked with two bands of 

 black. {See jplate^ page 64-.) 



