
AQUATIC INSECTS OF FRESHWATER 

food for many of the larger insects, young fishes, etc. Net- -winged 
Midges are a very numerous family of hanaree of genera and species. 
Aguatic Fiies. Some of the flies frequent water courses, ponds and 
pools in which they deposit eggs and where they pass che larval and 
pupal stages. Among these are the Moth-like flies of the family Psycho- 
dide; the Crane-flies of the families Tipulide, Syrphide and Muscide; the 
False Crane-flies, Rhyphide; the Black-flies, Empidide; and the Buffalo-flies, 
Simulide; Fig. 213; the Horse-flies, Tabanide; the Soldier-flies, Stratio- 
myiide; the Snipe-flies, Leptide; the Long-legged Flies, Dolichopodida; 
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. 
Orper Coreoprera. Of this order a number of families are aquatic. 
They have a pair of veinless horny wing covers or elytra, occupying the 
position of the 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 of 
Coleoptera occur in America north of Mexico and over 11,000 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 
Dytiscide; the Water-scavenger beetles and Great Water-beetles or 
Hydrophilide, the Whirligig-beetles or Gyrinide; the Pond-beetles 
or Haliplide; and many other smaller beetles belonging to these genera. 
Prepaceous Divinc-BeeTLtes or Warter-Drvers belong to the 
family of Dytiscide and are brownish-black shining beetles of oval form 
with threadlike antenne. 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 larve are known as Water-tigers, 
Fig. 222, most ferocious enemies to all living water animals, 
some of them growing to a length of 21% inches. ‘They have 

an elongated spindle form with a large head, and strong, 
* FIG. Bas curved and hollow mandables for holding and sucking the 
ater-tiger,. arva 
ofa Predaceous. juices of their prey. The segmental body has six legs and 
Deine ; ; ; ; a : 
iving-beetle. —_ terminatesina pair of breathingtubes. Theeggs are deposit- 
268 
