Fig. 246. — Black-fly (Simulium mo- 

 lestor), enlarged; at the left, a 

 more enlarged view of the aquatic 



young. 



INSECTS. 



257 



Every traveler, at certain times of the year, in our northern w l s 



becomes well acquainted with that pest, the black-fly. I, h , , lua „ ^ 

 with black body and transparent wings; but 

 the torment that it can cause bears no relation 

 to its size. Still, it can hardly compare with 

 some of its relatives in warmer countries. Thus 

 in the region of the Black Sea there is a spe- 

 cies which frequently kills cattle by the inflam- 

 mation ensuing from its bites, while in our 

 southern states the allied ' buffalo-gnat ' is 

 almost equally destructive. Its bite produces 

 an inflammation, and death frequently follows, 

 accompanied with severe cramps and convul- 

 sions. The larva? of these various black-flies 

 are like those of the mosquito, in the fact that 

 they live in the water, though they differ in 

 many points of structure. 



The mosquitos, of which there are many species, are too well known 

 in their adult condition to need any extended description. The females 

 lay their eggs in small masses on the surface of stagnant water, each 

 mass resembling somewhat in shape the peel of a quarter of an orange. 

 The eggs are arranged at right angles to the surface of this float, 

 and when they hatch the larvae escape from the lower ends of the eggs 

 directly into the water. Here they feed upon the abundant decaying 

 vegetable matter, and soon become large enough to be readily seen, and 

 from the peculiarities of their motions they have received the appropriate 

 name of wrigglers. They make their way quickly through the water by 

 the contortions of their body, and then they will remain quiet for a few 

 moments, when the buoyancy of their bodies 

 brings them, tail uppermost, to the surface 

 of the water. At the extremity of the body 

 there is a small tube, fringed with hairs, and 

 through this the larva breathes air when at 

 the surface. A few moments are sufficient to 

 ■obtain a sufficient supply, and then the larva 

 wriggles its way to the bottom again. 



With growth the larva molts two or three 

 times, and then changes to the pupal condi- 

 tion, which differs in several respects from the larva, as is shown in tin- 

 cut. The breathing-tubes have changed to the sides of the thoracic region, 

 ■and so now, when it comes to the surface for respiratory purposes, it con 



Fig. 247. — ' Wrigglera,' th< young of tlie 

 mosquito. A, larva: /.' pupa 

 d indicate the openings through which 



the air for respiratory put 



