THE HABITS OF CERTAIN SARCOPHAGID^. 27 



As usual we were forced to do what could be done with such oppor- 

 tunities as were offered. It was decided to institute at once a new 

 series of studies upon the relations of the American sarcophagids 

 to the gipsy moth, and to conduct them so carefully that if they did 

 not produce positive results they would at least possess negative value. 

 Fortunately the services of Mr. Patterson were available at that 

 time, and the affairs of the laboratory were in such condition as to 

 permit him to give the work his undivided attention. For the first 

 time it was possible to conduct the experiments, which he will de- 

 scribe himself, with the adequate attention to detail which is abso- 

 lutely necessary if the results are to be considered as decisive. His 

 results seem to justify the retention of the ideas previously held, 

 in so far as they can be justified by a study of American conditions. It 

 is sincerely to be hoped that in the very near future similar investi- 

 gations may be conducted in Europe, since the only other additional 

 studies which seem worth while in America will be of the sarcopha- 

 gids in relation to other lepidopterous hosts, and the findings, what- 

 ever their character, would not be directly applicable to the problem 

 of gipsy-moth parasite introduction. 



GENERAL CONDITIONS. 



Since the establishment of the Gipsy Moth Parasite Laboratory in 

 1905 considerable interest has been excited each year from the number 

 of sarcophagids reared in connection with gipsy-moth pupse, and even 

 more from the larger percentage of sarcophagids received from gipsy- 

 moth pupaj imported annually from Europe and Japan. It would 

 seem probable from the above that certain species of sarcophagids 

 had always been parasitic, or else that they had within recent years 

 developed the parasitic habit, which is the more likely ; hence, instead 

 of having to depend wholly upon dead material as a host they had 

 joined the ranks of certain of the Tachinidse in waging war against 

 one of the most injurious insect pests that has ever invaded New Eng- 

 land, the gipsy moth. During the last few years certain tentative 

 experiments have been made at the laboratory, but all this work, while 

 it proved rather interesting, was not convincing, and gave neither 

 positive nor negative results. In the summer of 1910 conditions 

 again became favorable for further investigations into the habits of 

 native Sarcophagidse and the writer attempted to determine, by the 

 series of experiments which follow, whether any of these flies are 

 parasitic in habit, or whether they are scavengers on the gipsy moth. 



COLLECTIONS OF GIPSY-MOTH PUP^ FOR MAGGOTS OF 

 SARCOPHAGIDS. 



Collections were made of gipsy-moth pupae from localities in towns 

 within a radius of 10 miles of the laboratory. The smallest collec- 

 tion contained 225 and the largest 790 pupa?, each of which was care- 



