THE HABITS OF CERTAIN SABCOPHAGIDiE. 29 



dead gipsy -moth pupa was accidentally broken off in removing it from 

 the tree, thus disclosing within its almost empty case 2 third-stage 

 maggots, one Compsilura concinnata and the other a sarcophagid. 

 This may be very satisfactorily explained by the fact that this pupa, 

 when in the caterpillar stage, was first parasitized by Gompsilura con- 

 cinnata^ and after reaching the pupal stage the maggot within became 

 large enough to kill the pupa. The decomposition which resulted 

 furnished a favorable place for the oviposition of a female sarcoph- 

 agid. In various other cases, when it appeared as an almost absolute 

 certainty that maggots of the Sarcophagidse came from living mate- 

 rial, their presence could be accounted for in some such way as the 

 above. The following experiments with the native sarcophagids will 

 also go to strengthen and substantiate the above theory. 



EXPERMENTS WITH ADULT SARCOPHAGID-ffi. 



Collections were made of these flies for reproduction experiments 

 from different localities in the infested area. Each collection was 

 kept separate in cylindrical wire screen (one-twelfth-inch mesh) 

 cages, 10 inches in height by about 4 inches in diameter. The top 

 consisted of a circular piece of wood, to which was tacked the wire 

 screen, while the lower edge of the screen fitted into a groove in the 

 wooden base. This arrangement allowed the quick removal of the 

 base and furnished easy access to the cage. A sprig of leaves, with 

 the stem wrapped with cotton batting, was inserted in a tube of 

 water attached to the inside of each cage, and this was sprayed with 

 a solution of sugar and water twice daily, which furnished food for 

 the flies. At first only active prepupal larvae of the gipsy moth were 

 placed in these cages. They pupated in a day eg: two and were al- 

 lowed to remain there for several days, where the flies could have free 

 access to them, before they were transferred to jelly glasses, which 

 were covered with cheesecloth. These were kept under observation 

 for sarcophagid maggots until the moths emerged or the pupae died, 

 in which cases they were always dissected. All these experiments 

 gave negative results, showing almost conclusively that these flies 

 did not oviposit on living pupse. The writer then added some badly 

 decomposed caterpillars to the living ones in the cages and observed 

 in a short time that the female flies deposited tiny maggots on the 

 dead material, but not on the living, although frequently they 

 crawled over the live pupae until these wriggled, which seemed to 

 frighten the flies away. The living material from these experiments 

 was also placed in jelly glasses, but all finally gave negative results. 

 All dead material was now placed in the cages and first-stage mag- 

 gots were obtained quite plentifully and appeared to be perfectly 

 healthy. 



