BUTTERFLIES OF THE DISTRICT OF COLUMBIA 177 



chusetts, where it seems to be merely a variant of the local Argynnis 

 aphrodite aphrodite. 



So far as I have seen, there is little difference between early and 

 late spring individuals in size or color, but the later ones are less 

 hairy. 



Speaking of P. philenor^ Lord Kothschild and Dr. Karl Jordan 

 wrote that the spring specimens appear on the whole to be smaller 

 than the later individuals, and bear always a row of spots on the 

 upper side of the fore wing, this row being often absent from the 

 males of the summer brood (or broods). The hairiness of the body 

 varies considerably, early Californian specimens having quite a 

 shaggy appearance. The difference between spring and summer indi- 

 viduals, according to my observations, reaches its maximum in the 

 District. i 



In the summer brood the fore wings in both sexes vary from 45 mm. 

 to 55 mm. in length, being usually about 50 mm. long; in occasional 

 individuals they may reach nearly or quite 60 mm. 



It is a matter of considerable personal interest to me that I was 

 so fortunate as to have been able to show Dr. Karl Jordan, the lead- 

 ing authority on the Aristolochia swallowtails, the first living indi- 

 vidual he ever saw. Before his visit to Washington a few years ago 

 his experience in the field had been confined to Europe and Africa, 

 where no species of this group occurs. While he was here we made 

 a trip to Cabin John together, and he was lucky enough to catch a 

 specimen of the rare spring form of P. philenor — which, incidentally, 

 was the first example of it I ever saw. 



Caterpillar. — The fully grown caterpillar is somewhat more than 

 2 inches in length, cylindrical, black or blackish, with large fleshy 

 filaments along the sides of which the pair on the first segment are 

 very long, nearly twice as long as any of the others, and are directed 

 outward, upward, and a little forward. 



When young the caterpillars are gregarious, ranging themselves 

 side by side along the edge of a leaf and at right angles to the latter. 

 Later they are sociable, though not gregarious, but in the last stage 

 they are solitar}^ and are found generally distributed over the food 

 plant. Large caterpillars in confinement are likely to turn cannibal 

 and eat one another. 



The caterpillar feeds on the dutchmans-pipe {Aristolochia sipho), 

 on the Virginia snakeroot {A. serpentaria) , and occasionally on re- 

 lated plants. It sometimes does great damage to the first named 

 when it is grown as an ornamental plant. 



Chrysalis. — The chrysalis is very easily distinguished from that 

 of our other local swallowtails. The ventral surface is swollen, and 

 when the chrysalis is viewed from the side it appears to be strongly 

 bent in the middle. When viewed dorsally the abdomen is seen to be 



