AQUATIC INSECTS OF FRESHWATER 



food for many of the larger insects, young fishes, etc. Net-winged 

 Midges are a very numerous family of hundreds of gene'ra and species. 



Aquatic Flies. Some of the flies frequent water courses, ponds and 

 pools in which they deposit eggs and where they pass the larval and 

 pupal stages. Among these are the Moth-like flies of the family Psycho- 

 did<£\ the Crane-flies of the families Tipulid^, Syrphid^ and Muscida; the 

 False Crane-flies, Rhyphida; the Black-flies, Empidida; and the BufFalo-flies, 

 Simulid^; Fig. 213; the Horse-flies, Tabanida; the Soldier-flies, Stratio- 

 myud^\ the Snipe-flies, Leptida; the Long-legged Flies, Bolichopodida; 

 and many others, far too many and too complex in classification for further 

 description in a volume of this character. The aquatic genera are all 

 harmless to young fishes and constitute a part of their natural food. 



Order Coleoptera. Of this order a number of families are aquatic. 

 They have a pair of veinless horny wing covers or elytra, occupying the 

 position ofthe fore wings, folded and meeting in a straight line down the back, 

 under which is a single pair of membranous wings, though some species have 

 the rudiments of fore wings under the elytra. More than 80 families ot 

 Coleoptera occur in America north of Mexico and over 1 1,000 species 

 have been described. The most generally distributed genera and species 

 of the Eastern section of the United States, which for either a part of, or 

 their entire existence, inhabit the water,are the Predaceous Diving-beetles or 

 Dytiscids; the Water-scavenger beetles and Great Water-beetles or 

 Hydrophilidae, the Whirligig-beetles or Gyrinidse; the Pond-beetles 

 or Haliplidse; and many other smaller beetles belonging to these genera. 

 Predaceous Diving-Beetles or Water-Divers belong to the 

 family of Dytiscidse and are brownish-black shining beetles of oval form 

 with threadlike antennae. The anterior and middle legs are adapted for 

 crawling, the posterior legs are longer, fringed with hairs 

 and adapted for swimming. They abound in ponds and 

 still water, sometimes in streams. The breathing apparatus 

 is located at the hind end of the body, the beetle at rest 

 floating on the water in an inclined position, head down- 

 ward, and by slightly raising the wing covers admits air 

 under them for breathing under the water. They are 

 voraceous and attack all water animals, even large fishes, 

 frogs and snakes. The larvae are known as Water-tigers, 

 Fig. 222, most ferocious enemies to all living water animals, 

 some of them growing to a length of 2 ^ inches. They have 

 an elongated spindle form with a large head, and strong, 

 FIG. 222. curved and hollow mandables for holding and sucking the 

 of a Predaceous juices of their prey. The segmental body has six legs and 

 mng- eet e. terminates in a pair of breathing tubes. The eggs are deposit- 



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