210 THE CANADIAN ENTOxMOLOGLST. 



into the ground. Here it contracts to the pupa state, and in a few days 

 issues as a large two-winged fly, which I have described (Joe. cit.) as 

 Sarcophaga sarracaiice — tlie Sarracenia Flesh-fl\^ 



The immense prolificacy of the flesh-flien, and the fact that the young 

 are hatched in the ovaries of the parent before they are deposited by her 

 on tainted meat and other decomposing or strong-smelling substances, 

 have long been known to entomologists, as has also the rapid develop- 

 ment of the species. The viviparous habit among the Muscidse is far 

 more common tlian is generally supposed, and I have even known it to 

 occur with the common house-fly, which normally lays eggs. It is also 

 possessed by some CEstridae, as I have shown in treating of QLsinis ovis, 

 the Sheep Bot-fly,''' 



But the propensity of the larvae for killing one another, and their 

 ability to adapt themselves to different conditions of food supply are not 

 sufiiciently appreciated. I have long since known, from extensive rearing 

 of parasitic Tachinidte, that when, as is often the case, a half dozen or 

 more eggs are fastened to some caterpillar victim only large enough to 

 nourish one to maturity, that they all hatch and commence upon their 

 common prey, but that the weaker eventually succumb to the strongest 

 and oldest one, which finds the juices of his less fortunate brethren as 

 much to his taste as those of the victimized caterpillar. Or, again, that 

 where the food supply is limited in quantity, as it often is and must be 

 Avith insects whose larvDS are parasitic or sarcophagus, such larvae have a 

 far greater power of adapting themselves to the conditions in which they 

 find themselves placed, tlian have herbivorous species under like circum- 

 stances. 



Both these characteristics are strongly illustrated in Sarcop/iaga 

 sarrace/iice. Several larvae, and often upward of a dozen, are generally 

 dropped by the parent fly within the pitcher ; yet a fratricidal warfare is 

 waged until usually but one matures, even where there appears macerated 

 food enough for several. And if the Xanthoptera larva closes up the 

 mouth of the pitcher ere a sufficient supply of insects have been captured 

 to properly nourish it, this Sarcophaga larva will nevertheless undergo its 

 transformations, though it sometimes has not strength enough to bore its 

 way out, and the diminutive fly escapes from the puparium, only to find 

 itself a prisoner unless deliverance comes in the rupture or perforation of 

 the pitcher by the moth larva or by other means. This rupturing of the 



■' IstMo.jEnt. Rep., p. 165. 



