460 



THE STUDY OF INSECTS. 



The antennse are small and short ; the third segment is 

 simple and furnished with a slender, jointed, terminal style. 

 The proboscis is usually long, sometimes very long, and 



V3 + vnx 



Fig. 555. — Wing of Rhynchocepkahis sackeni, 



fitted for suckine nectar from flowers. Onlv four North 

 American species have been described ; and these are all 

 rare. 



Family AsiLiDiE (A-siri-dae). 



The Robber-flies. 



These are mostly large flies, and some of them are very 

 large. The body is usually elongate, with a very long, 

 slender abdomen (Fig. 556); but some species are quite 

 stout, resembling bumblebees in form. This resemblance is 

 often increased by a dense clothing of black and yellow 

 hairs. 



In this and the following family the vertex of the head 



Fig. 556. — Erax a^zcali's dtstroyjng 

 a cotton-worm. (From the Au- 

 thor's Report for 1879.) 



Fig. 557. — Head of 

 robber-fly. 



Fig. 558. 



is hollowed out between the eyes (Fig. 557). In this family 

 the proboscis is pointed and does not bear fleshy lips at the 



