CARNIVOROUS BUTTERFLIES — CLARK 455 



Mr. Kershaw only found the larvse feeding on two kinds of aphids, 

 though he says they doubtless eat other kinds. One was slate- 

 colored with a white efflorescence (as is the Schizoneura of the alder, 

 the favorite food of F'eniseca tarquinius) , the other greenish with 

 four dark-green patches, some of them being fringed with white, 

 probably molted skins. 



He was not sure, but had some reason for believing, that the larvae 

 tend to resemble in color the aphids upon which they happen to be 

 feeding. At first, as the eggs had been laid amongst the green 

 aphids, he fed the larvae upon these; but, a typhoon having washed 

 away the food supply, he could thereafter find only the slate-colored 

 species which, however, the larvae seemed quite as much to enjoy. 

 But he noticed soon after that the colors faded, and the purple- 

 brown tended to mingle with the yellow. 



Mr. Kershaw says that one of the features of this curious life his- 

 tory is the calm way in which the caterpillar moves among the 

 aphids and selects its prey, and the indifference with which the lat- 

 ter apparently accepts its fate. 



AVlien about to pupate the caterpillars walk about at quite a fair 

 rate of speed and, having chosen a spot, spin a few threads a little 

 distance from head and tail. Mr. Kershaw's larvae pupated on a 

 piece of bark, one putting a band about its middle and pupating 

 horizontally, the other pupating vertically and without a band, 

 though both had the threads (not attached to the pupa) at head 

 and tail. 



The tail of the pupa is cut off squarely, forming a disk, thus 

 securing a good hold, probably sufficient without the band around 

 the middle. It seems to be affixed with some secretion, not actual 

 threads. There is a small process on either side of the third segment 

 from the tail. 



The pupal stage lasts about 10 days. As the larval stage lasts 

 about 15 days and the eggs require 4 days to hatch the time occu- 

 pied in the various transitions from the freshly laid egg to the 

 emergence of the butterfly is about 29 days, or about a week longer 

 than in the case of Feniseca tarquinius. 



Both larvas and pupae struck Mr. Kershaw as small in compari- 

 son with the size of the butterfly. 



Both the males and females of this butterfly, according to Mr. 

 Kershaw, are very fond of the exuding juice of the plants upon 

 which the larvae live. Half a dozen may occasionally be seen close 

 together on a leaf or stem drinking this sap, thrusting their tongues 

 into any interstices left by the aphids. 



It seems to me that what the butterflies are drinking is probably 

 not the plant juice, but the exudations from the aphids which have 

 fallen on the plants. 



