1894-] ENTOMOLOGICAL NEWS. 173 



ON THE HABITS OF SOME ASILID/E. 

 By T. D. A. COCKERELL. 



The article in the April NEWS, on the "Bold Robber Fly," 

 induces me to send you the following- notes on Asilidae which 

 were prepared for one of our N. Mex. Station Bulletins, but 

 crowded out in publication. All the observations recorded were 

 made between Las Cruces and the Agricultural College, in the 

 Mesilla Valley, New Mexico, altitude 3800 feet. 



I am indebted to Messrs. Coquillett and Johnson for the iden- 

 tification of the flies, and to Mr. Fox for reporting on the Hy- 

 menoptera mentioned. 



Erax dubius Will. 

 Erax cinerascens Bell. 



These two flies belong to the family Asilidae, the species of 

 which are recognized by their long tapering bodies and usually 

 large size. Flies of this family prey on other insects, and are 

 often to be accounted useful, but unfortunately they also prey on 

 one another. Both the above species were taken from the clutches 

 of other Asilids: Erax dubius from a large kind known as Proc- 

 lacanthus philadelphicus, the other from a kind not identified. 

 This was on July 28th. 



Mallophora fautrix O.-S. 



A fly over half an inch in length, with brown wings, face with 

 a yellow beard, scutellum and abdomen above yellow, thorax and 

 legs black. On July 28th one was taken, which, like the last 

 two species, had been caught and killed by a large Asilid. On 

 August 5th, however, I found one which had itself caught a wasp 

 {Odynerus sp. near propinqwis}. 



Thus it appears that a fly, which is able to capture and kill 

 wasps, is nevertheless itself liable to be killed by another fly. 

 This quite reverses one's natural idea that a wasp, with its sting 

 and hard body, would be superior to any fly. 



On July 2Sth another JMallophora (which Mr. Johnson says is 

 a new species, unless described from Mexico) was caught with a 

 honey bee in its clutches. 



Proctacanthus philadelphicus Macq. 



A large Asilid fly over an inch and a quarter long. As related 

 above, one was found preying on Erax. On July 28th I also 



