DIPTERA OF MINNESOTA. 



87 



Their prey is always taken upon the wing, and their appetite is evi- 

 dently hard to satiate, one individual having been observed to kill 

 eight moths one after the other. 



They vary in size from one-third of an inch or smaller to species 

 two inches or more in length. Our illustrations give an idea of the 

 difference in appearance between some of the species. Cyrtopogon 

 bhnacula, Walk., Fig. 78, is nearly an inch long, the general color 

 being black, the wings clear with black markings ; Dasyllis thoracica. 

 Fab., Fig. 79, is shiny black, with a profusion of yellow hairs on the 

 thorax, and on the head between the eyes. Fig. 80 illustrates one of 

 the more delicate forms, Stichopogon trifasciatus, about two-thirds of 

 an inch long, head and thorax pearl, abdomen black with pearl col- 

 ored lines where the segments meet, and a broad band of the same 

 color on the fourth abdominal segment. Promachus vertebratus, Say, 

 Fig. 81, one of our largest species, and very common, the writer has 

 seen flying off over a wheat field with a good sized grasshopper in its 

 grasp. Laphria sericea, Say, is shown in color, natural size, as Fig. 

 21, Plate II; Dasyllis sacrator, Walk., Fig. 10, Colored Plate II, looks 

 something like a large bumble bee. All the above species occur in 



Fig. 79. Dasyllis thoracica. Original. 



Stichopogon trifasciatus. Original. 



Minnesota, as does also Proctocanthns brevipennis, Wied., which looks 

 something like a small edition of P. vertebrata; P. milbertii, Macq. ; 

 Tolmerus notatus, Wied.; Brax rufibarbis, Macq., and B. aestuans, 

 Linn.; Cyrtopogon falto, Walk.; Taracticns octopunctatus, Say; Lep- 

 togaster incisuralis, Loew. ; L. ilavipes, Loew. Several other species 

 belonging to the genus Asilus are yet to be named. 



