April, '15] ALDRICH: SARCOPHAGID^, ECONOMIC RELATIONS 243 



the records accumulated up to the present, and many of them are of 

 considerable interest. Schiner in his Fauna Austriaca expressed a 

 doubt whether the few recorded cases of his day might not be explained 

 as carrion-feeding, the insects having died before the eggs of the fly 

 were laid; and his doubt has curiously persisted and found frequent 

 expression almost to the present time. But the large number and 

 variety of the cases now^ known, many of them closely studied, permit 

 no further doubt that Sarcophagas are generally parasitic in their 

 habits. At least this is true with many of the species. 



There are two records of rearing from scorpions, one from Sumatra 

 of an undetermined species, the other S. sternodontis from one in 

 Jamaica. 



Egg-sacs of spiders furnish a nidus for davidsonii, reported only 

 from California. 



The adult of Corydalis cornuta has been attacked by Sarcophaga 

 helicis, a series of bred flies with data being in the National Museum 

 collection, dating from Riley's time. 



Grasshoppers have furnished a large amount of bred material in 

 several species: S. helicis, hiinteri, sarracenice, kellyi, and the species 

 heretofore erroneously known as dmbicis, are the ones most frequently 

 bred in the West; of these kellyi is undoubtedly the commonest one. 

 Mr. E. 0. G. Kelly, in the Journal of Agricultural Research for Sep- 

 tember 21, 1914, has described its egg-laying habit. The female darts 

 at the flying grasshopper and strikes it with enough force so that it 

 instantly drops to the ground, when the larva of the fly can be found 

 attached by a gluey secretion to the thorax or base of the wing. The 

 fly also deposits larvae on the quiescent, newly-moulted adult hopper 

 while it is hardening, this involving an instinct-stimulus quite different 

 from the other case. 



A western species closely allied with erythrura of Europe has been 

 found abundantly about grasshoppers in Colorado; the female fly 

 has a fairly well-developed larvipositor, and presumably inserts its 

 young under the body wall of the hopper, though this has not been 

 observed. There is every reason to believe that in the arid west grass- 

 hoppers are normally kept within moderate numbers principally 

 through the agency of the Sarcophagid parasites. In the east these 

 are not so frequently reared; sinuata, sarracenice and helicis have been 

 reported. | 



A specimen of Cicada tihicen was sent in to the Bureau of Ento- 

 mology in August, 1894, from Waterfield, Va.; it was dead when re- 

 ceived, and a number of dipterous larvae had emerged, from which 

 subsequently developed the ubiquitous S. helicis. 



The question whether Sarcophagids are anything more than scaven- 



