114 
Psyche 
[December 
a return to a past carnivorous diet. Orfila believes that the 
original diet was vegetable, and while he points out that 
sporadic cannibalism may be the forerunner of a more wide- 
spread carnivorous diet in the future, he leans toward the 
belief that cannibalism is due to an upset in internal organic 
conditions. Berg (1892) maintained that climatic condi- 
tions (in Patagonia) caused the supply of food plants to 
diminish so that larvae were driven to cannibalism by hunger. 
This is undoubtedly correct. He further maintained, how- 
ever, that the cannibalistic character was inherited, and that 
many larvae could not return to a vegetable diet after having 
e^ten meat. It is not improbable that natural selection could 
be responsible for the high percentage of cannibalism found 
in many species. I have observed, however, that our native 
species will return to a vegetable diet if given the oppor- 
tunity. Schultz (1935) is of the opinion that cannibalism 
may be due not only to hunger but also to a need for satisfy- 
ing thirst. Without a doubt thirst is a contributing factor. 
This much may be said, that cannibalism may be induced 
experimentally by crowding and by an insufficient food 
supply, but that it appears to crop out under conditions of 
favorable population densities and food supply as well. It is 
not improbable that this phenomonon will be found to be 
more widespread in lepidopterous larvae than is realized at 
the present time. Thus far cannibalism has been reported 
in Geometridae, Noctuidae, Arctiidae, Saturniidae, Bombycidae, 
Sphingidae, Danaidae, Nymphalidae, Papilionidae, Pieridae, 
and Lycaenidae. It does not appear, however, that larvae are 
forced to adopt a meat diet under favorable conditions but 
simply do so accidentally when in close proximity to another 
individual. Or, they may attack when unduly disturbed, and 
having tasted meat, continue to eat more or less automati- 
cally as long as its taste is not repellent. Larvae taken off a 
meat diet will survive with no apparent ill effects on a normal 
vegetable diet. 
LITERATURE CITED 
Berg, C., 1875. Patagonische Lepidopteren. Bui. Soc. Imp. Nat. 
Moscou, 49(2) : 191-193. 
1892. Canibalismo entre insectos. Anal. Soc. Cient. 
Argentina, 34: 386-388. 
Bird, H., 1925. New life histories in Papaipema No. 23 (Lepidoptera). 
Canadian Ent., 57(12) : 305. 
