174 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.48. 



Genus LORDOTUS Loew. 

 LORDOTUS GIBBUS Loew. 



Common on mesa after August 1 . 



Family ASILIDAE. 

 Genus HETEROPOGON Loew. 



HETEROPOGON SENILIS Bigot. 



One specimen from Eagle Tail Mountain, 7,500 feet. 

 Genus MALLOPHORA Macquart. 



MALLOPHORA GUILDIANA Williston. 



One specimen from foothills July 29. 



MALLOPHORA CLAUSICELLA Macquart. 



One specimen from mesa August 5. 



Genus PROCTACANTHUS Maequart. 



PROCTACANTHUS MILBERTII Macquart. 



This large species swarms over the plains during the hottest part of 

 the day. It feeds largely upon half-grown grasshoppers. One indi- 

 vidual was found to have a medium sized stout skipper butterfly in 



its grasp. 



Genus STENOPOGON Loew. 



STENOPOGON PICTICORNIS Loew. 



Very common on mesa. Recorded as eating Hemileuca by Mr. C. N. 

 Ainslie but also feeds largely upon grasshoppers, butterflies, etc. 



Genus OSPRIOCERUS Loew. 



OSPRIOCERUS ABDOMINALIS Say. 



Found rather commonly at all elevations. Flies heavily and is 

 easily captured. 



OSPRIOCERUS MINOS Osten Sacken. 



Equally abundant and often found in company with the preceding 

 species, of which it may be merely a color phase. A specimen had 

 killed and was devouring another of the same species. 



Genus ERAX Scopoli. 

 ERAX STAMINEUS Williston. 



Rather common on the mesa during early August. 



ERAX VARIPES Williston. 



Equally common and found with the preceding species. 



Genus DEROMYIA Philipi. 

 DEROMYIA PERPLEXA Back. 



The commonest Asilid on the mesa during early August. One 

 individual was devouring a beetle of the genus Hister. 



