DIPTERA. 



53 



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

 the mouth armed with two mandibles, devour the lar\\T2 of their 

 hosts, the bees. This is the return 

 they make for the hospitaUty they 

 have received ! 



The Hclophili (Fig. 39; deserve 

 to be mentioned here on account 

 of the singular form of many of 

 their larvse. The head is thick, 

 fleshy, and varying a Httle in form. 

 But the point by which they are 

 easily to be distinguished from 

 most other larv^ 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 oi a Helophilus. 



habits are aquatic. Having placed some 01 them in a bason of 

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

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



