130 GNATS OR MOSQUITOES — CHAPTER VII 



much the same position as those of Culejc, but perhaps 

 the breathing horns are held, sloped somewhat more fore- 

 wards. JEdes larva? are said, by Dr. Lutz, to lie in the 

 water in a sloping position, intermediate between that of 

 Anophehfi and Cidex, in other words, much as do those of 

 Stegomijia. According to Meinert, Corethra larva^ are 

 much less restricted as to the character of the collections 

 of water in which their larva? are reared being often found 

 in deep still water containing but little vegetation, as well 

 as in very foul pools. Their position in the water is even 

 more absolutely horizontal than that of Anopheles, whose 

 position is slightly oblique, and they retain this horizontal 

 posture even during their excursions below the surface. 

 They are very voracious, devouring not only Daphnia' and 



Fig. 31. — Larva and Nymph of Anopheles, to show habitual resting posi- 

 tion. The head of the larva is shown looking up, as when feeding. 



other small crustaceans, but also Dixa larvae and even young 

 fish and molluscous embryos ; nor do they even shrink from 

 cannibalism, smaller specimens of their own species being 

 devoured with gusto if they come within the reach of their 

 jaws. It is only the very young larvae that are so abso- 

 lutely transparent, as when older they develop a number of 

 patches of pigment, and the contents of the intestinal canal 

 obscure the complete transparency of the body. Still, it is 

 doubtless owing to this transparency that they are the only 

 gnats whose larva^ live, as a rule, among fishes. All their 

 ecdyses are performed with singular rapidity, even the final 

 emergence of the imago taking only a few minutes to 

 accomplish. Their pupa^ assume a nearly vertical position 

 in the water, but otherwise do not differ greatly from 

 those of other genera. 



