4G DKAGON FLIES VS. MOSQUITOES. 



the egg development of Diplax minutely, and we can add 

 nothing to his fnll details. 



Odonat larvie are sluggish and unable to make quick, 

 well directed movements of the whole body. The powers 

 of locomotion are very poor when their predatory habits 

 are considered ; the legs are feeble and used for crawling 

 and burrowing in the mud. The larva, however, possesses 

 a locomotory power which is derived from its ability to 

 suddenly force out the water contained in its abdomen, 

 thereby propelling the body forward for some distance ; 

 but this function is not entirely under control, the larva 

 cannot always strike the desired point. It is here that a 

 most remarkalde structure plays an important part. On 

 turning over one of these insects it will be found that the 

 under lip is greatly enlarged and is folded over the mouth 

 parts so as to earn the name of " mask." Plate V., Figs. 

 3 and 5, show how it is hinged, and the formidable ex- 

 tremity. It seems that all the muscular energy and 

 powers of quick perception were attached to this organ. 

 Nothing can exceed the rapidity with which the mask is 

 shot forward and its helpless prey is seized. Then this 

 arm-like lip is used as a fork to hold the food which it 

 slowly feeds into the capacious jaws. The size and struct- 

 ure of this '* mask " clearly indicate, in our opinion, that 

 such puny victims as Culicid larvse were never intended 

 as the natural food to be seized by an appendage Avhich is 

 capable of catching and firmly holding prey quite as large 

 as the insect to which the mask belongs. Packard ^^^ 

 regards the Odonata as scaveno-ers ; he savs: "In the water 

 they prey upon young mosquitoes and the larvse of other 

 noxious insects, * * * j^i^j cleanse the swamps of 

 miasmata." If, as stated by the same author, mosquitoes 



