AMERICAN DIPTERA. 189 



This species differs from abdominalis in no respect except 

 that the venter is largely yellow and there is no black upon 

 the lateral margins. Mr. Coquillett writes that the venter is 

 sometimes wholly yellow, while in other specimens the last 

 two segments, except the base of the penultimate, are black. 

 There are six specimens of this species in the collection of the 

 Am. Ent. Soc. which Dr. Skinner told me were collected, so 

 far as he could remember, at the same time and under the 

 same conditions as were specimens of abdominalis. This, to- 

 gether with the fact that the Brooklyn Institute possesses a 

 specimen which has the venter black except the base of each 

 segment, leads me to wonder whether ventralis may not some 

 day be proved to a variety of abdominalis. 



Prof. J. M. Aldrich writes that the species of Ospriocerus, 

 Stenopogon, Deromyia and Saropogon bite most viciously when 

 caught and held between the fingers, jabbing in a most effec- 

 tive manner with their sharp proboscis, the resulting sensation 

 being like that of a bee sting, only does not last so long. The 

 writer has had the same experience with Deromyia in Flordia. 

 Prof. Aldrich says that he has had no other Asilids or other 

 flies to bite under similar circumstances. 



In speaking of the distribution of Ospriocerus and Sten- 

 opogon, Prof. Aldrich states that they do not occur in eastern 

 South Dakota, but are, in going westward in the State, first 

 met with in the center of the State, at the beginning of the 

 more arid regions, and that in northern Idaho specimens of 

 these species are rare except in the low altitudes of Lewiston 

 and vicinity, where more arid conditions exist than at Moscow. 



STENOPOGON. 



Stenopogon Loew, Linnaea Ent., II, 453, 1847. 



Stenopogon Schiner, Fauna Austr., I, 127, 1862. 



Scleropogon Loew, Cent., VII, 45, 1866. 



Scleropogon Schiner, Verh. Zool.-Bot. Ges., 1866, 846; quotes 



orig. desc. 

 Stenopogon Coquillett, Pr. Ent. Soc. Wash., VI, 179, 1904. 



Usually species of medium to large size. Front tibiae with- 

 out terminal claw-like spur, body elongate. Head narrow, 



TRANS. AM. ENT. SOC, XXXV. MAY, 1909. 



