460 



THE STUDY OF INSECTS. 



The antennae 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 



vn, 



FIG. 555. Wing of Rhynckocephalus sackeni. 



fitted for sucking nectar from flowers. Only four North 

 American species have been described ; and these are all 

 rare. 



Family ASILID^: (A-sil'i-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 afiicalis destroying 

 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 



