318 



Enemies of Bees — Robber Flies. 



and takes captive the bee and then feeds upon its fluids. It 

 is more common in the southern part of our country. The fly 

 (Fig. 1 72) has a long, pointed abdomen, strong wings, and is very 

 powerful. I have seen an allied species attack and overcome 

 the powerful tiger-beetle, whereupon I took them both with 

 my net, and now have them pinned, as they were captured, in 

 our College cabinet. These flies delight in the warm sunshine, 

 are very quick on the wing, and so are not easily captured. 

 It is to be hoped that they will not become very numerous. 

 If they should, I hardly know how they could be kept from 

 their evil work. Frightening them or catching with a net 

 might be tried, yet these methods would irritate the bees, and 

 need to be tried before they are recommended. I have re- 

 ceived specimens of this fly from nearly every Southern State. 

 During the past summer this same fly has been well employed 

 here in Mickigan. It has been observed to kill the cabbage 

 butterflies by scores. 



I have also a fly of the same family, with the same bee-de- 

 stroying habits, a species of Erax (Fig. 173). In form it re- 



Fig. 173. 



Ftr,. 174.* 



sembles the one referred to above. The wing (Fig. '17 4), as 

 will be seen, is quite different in its venation. I received this 

 species from Louisiana. Fig. 174, a, shows the antennae 

 magnified. The Nebraska bee-killer, Promachw baatardi, is 

 the same in general appearance as the above. The second vein 

 of the primary wing, not the third, as in case of Asilus, forks. 

 In Erax as seen in the figure, this branch Is disconnected. 



