DIPTERA. 



53 



;ggs therein. When these eggs have hatched, the larvae, which have 

 he mouth armed with two mandibles, devour the larvae of tlieir 

 losts, the bees. This is the return 



|:hey make for the hospitality they 

 lave received ! 



The Hclophili (Fig. 39; deserve 

 :o be mentioned here on account 

 >f the singular shape of many of 

 their larvae. The head is thick, 

 !leshy, and varying a little in form. 

 But the point by which they are 

 easily to be distinguished from 

 most other larvae is, that they have 

 always very long tails, sometimes, 

 indeed, out of proportion to the 

 length of the body. Reaumur called these larvae " vers a queue de 

 rat ;" they are known in England as rat-tailed maggots, and their 



Fig. 39. — A species of Helophilus. 



Fig. 40. — Larvae of Helophilus. 



habits are aquatic. Having placed some of them in a basin of 

 water, Reaumur saw that they kept in a perpendicular position at 

 the bottom of the basin, and parallel to one another, the extremities 



