DIPTERA OF MINNESOTA. 



91 



When disturbed these flics will dart away with wonderful speed, to 

 remain stationary in the air in another spot. These bee-flies, although 

 possessing a blackish grey ground color, are so densely covered with 

 pale yellow hairs that this color is entirely hidden. This hair is so 

 long that the outlines of the insects are obscured, and they resemble 

 on this account, very small bumble-bees." 



Fig. 85. Bombylius major. Original. 



SystropHS niacer, Loew, Lugger has reared from Limacodes in 

 Minn. 



THEREVIDAE. 



Stiletto-Flies. 



Possibly named from a fanciful resemblance to a stiletto; the 

 head is somewhat broad and the abdomen long and tapering. They 

 resemble somewhat some Asilids. We illustrate Thereva senex, Fig. 

 86, and T. frontalis, Fig 15, Colored Plate I, both taken in Minnesota. 



The family is a small one, predaceous in the adult and larval 

 forms upon insects in the young stage, probably feeding upon vegetable 

 matter also ; the larv?e of some species found in rotten wood. 



There are not more than 200 species of this family known over 

 the entire world; of these 71 species occur in North America. 



