SURROUNDINGS OF GROWING INSECTS 201 



of the pupa, similar to that characterizing the midges and gnats 

 just described, is found in the life-history of the blue-bottle 

 and the whole group of the muscoid flies. Some of the maggots 

 of these insects are adapted for life under water, and the allied 

 family of the Syrphidae affords an excellent and well-known 

 example of such adaptation in the curious " rat-tailed " maggots 



FIG. 105. 



a, Larva ("Rat-tailed Maggot") of Drone-fly (Eristalis), 



side view (s, anterior spiracle ; p, proleg ; /, spiracular tail 



region) ; b, puparium of Eristalis, dorsal view (s, spiracle ; 

 c, anterior horn). X 2^. 



(Fig. 105) of the drone-flies (Eristalis}. These insects resemble 

 bees in their hairy bodies and the manner of flight ; they may 

 be seen commonly in gardens hovering over flowers. Among 

 the maggots of the Syrphidae there is a tendency for the spiracles 

 at the hinder end of the body to be situated at the tip of promi- 

 nent outgrowths ; and in the remarkable life-relations of the 

 rat-tailed maggot we see the advantage resulting from an 

 extreme development of this tendency. This larva is an 



