LEPIDOPTERA 



71 



found on the milkweed from June till September. The 

 Silver-spotted fritillary (Argynis), whose larva feeds on 

 violets, and the mourning cloak (Vanessa antiopa), whose 

 larva feeds on willows and poplars, are easily secured for 

 study. The mourning cloak is the only kind of butterfly 

 frequently seen in February and March. 



Swallowtails. The swallowtails and their allies making 



FIG. 63 Common swallowtail, Papilio asterias ; A, larva; , preparing to 

 enter on the pupal state ; C, pupa as photographed twenty-four hours after. 



up the family Papilionidae have six perfect feet, and most 

 of the swallowtails are characterized by a projection at the 



posterior angle of 

 each hind wing. 

 They pass the win- 

 ter in the chrysalid 

 or pupal state, be- 

 ing always fastened 

 by a girdle near 

 the middle. The 

 larvae are naked 

 caterpillars, usu- 

 ally of a green 

 color, and feed upon a variety of plants. A most widely 

 distributed form is the cabbage butterfly (Pieris rapce), 



FIG. 64. Photograph of the common swallowtail, 

 Papilio asterias. One half natural size. 



