136 The Rocky Mountain Locust. 



I have also bred it from a number of our native locusts 

 whose carcasses — forsaken by the sarcophagous larvae — 

 may quite frequently be seen fastened to the upright stems 

 of different plants in the fall of the year. I have also bred 

 it from the common Carolina Mantis,* which it attacked 

 while living, and have known it to infest the common 

 Walking-stick {Spectrum femoratum). Indeed, the spe- 

 cies is a most widely-spread and general scavenger, occur- 

 ring in most civilized countries, and feeding, as a rule, 

 on dead and decaying animal matter, and only exception- 

 ally on living insects. By way of illustrating its trans- 

 formations, I introduce a figure of the Sarracenia Flesh-fly 

 which feeds on the dead insects caught in those curious 

 traps, the trumpet leaves {Sarraeenia) , and which is 

 probably only a variety {sarracenice, Riley) of carnaria.\ 

 These flies lay elongate and delicate eggs, which hatch 

 very quickly. They sometimes hatch, in fact, within the 

 ovaries, so that the fly gives birth to living larvae. These 

 are distinguished from those of the Tachina-flies by being 

 more concave and truncated at the posterior end (see Fig. 

 33, a). The Tachina larva is rounded posteriorly, with a 



* On the 18th of October, 1868, at South Pass, 111., I found fastened to a tree 

 a large female Mantis, still alive, but with the abdomen hanging down, partially 

 decomposed and filled with Sarcophaga larvae. These remained in the larva state 

 in the ground till the next July, but gave forth the flies at the end of that month. 

 The flies marked in my cabinet Sarcophaga caruaria, var. matitivora, differ in no 

 respect from the common carnaria, except in size, seven not averaging more 

 than 0.20 inch in length. 



t The flies bred from Caloptenus have the tip of the abdomen reddish, as in 

 Sarcophaga sarraceniai, and indeed are undistmguishable from the smaller speci- 

 mens of this last. The larva differs, however, in having the surface more coarsely 

 granulated, it being regularly and uniformly covered with minute papilke , in the 

 less conspicuous, prothoracic spiracles; in the smaller but deeper anal cavity ; and 

 in the rim of this cavity having the twelve tubercles more conspicuous. The 

 pupa also has the anal cavity smaller, more closed, but deeper; and the prothoracic 

 spiracles less prominent. In these respects it agrees more closely with the typical 

 carnaria, as described by Packard, and I have little doubt but all these differences 

 are simply varietal. 



