Ecological and Behavior Notes 63 



occasions we have noticed the carnivorous habits of this 

 robber-fly. Once it was seen devouring a grasshopper, 

 Melanoplus sp. [A. N. Caudell] nymph; again one was 

 flying from plant to plant as we pursued it, carrying 

 lightly a large sulphur butterfly, Colias philodice, upon 

 which it was dining — a pretty sight. Another had sub- 

 dued and was devouring so formidable an adversary as 

 Bomhus sp. [S. A. Rohwer]. 



Archytas aterrima R. D. [F. Knab]. In a curled up 

 leaf, which was spun together with silk threads, were a 

 Lepidopterous pupa and the puparium which gave forth 

 this Dipteron, side by side. 



Archytas analis Fabr. [C. T. Greene]. Thousands were 

 seen feeding on the flowers of Melilotus alba at Silica, 

 July 2, 1920. 



Chrysophila velutina Loew. Four of these were found 

 dead in a tiny streamlet at Wickes, July 12, 1917. Two 

 of these were parasitized by a tiny red mite. 



Helicobia halicis T. [C. H. T. Townsend]. An ant, 

 Formica pallidifulva Latr. [W. M. Wheeler] female was 

 seen going off at a galloping pace carrying this fly. The 

 fly was fresh and limp, but I do not know whether it was 

 newly killed or had been found dead. 



Syrphus americanu^ Wied. [C. T. Greene]. This fly 

 had fallen prey to a spider, Morptusa sp. [Emerton]. 



Erax rufibarbis Macq. [C. T. Greene]. Numerous on 

 the white sand flats at Silica, Mo., July 2, 1920. 



Calabata antennipes Say. [C. T. Greene]. Two speci- 

 mens seen on Cottonwood tree where the bark was de- 

 cayed, July 21, 1920. 



Conops brachyrhynchus Mocq. [C. T. Greene]. This 

 dipteron resembling a wasp was abundant at Silica, July 

 2, 1920. 



Slichopogon trifasciatus Say. [C. T. Greene]. These, 

 in intimate company mth Microbembix monodonta and 

 Philanthus politus Say, behaved and appeared in flight 



