Fig. 90—The young (nymph) of a dragon-fly. (From Kellogg's Amer. Insects.)
Fig. 91—The cast skin (exuvæ) of a dragon-fly nymph.
Fig. 92—Diving-beetles and back-swimmers. (From Kellogg's Amer. Insects.)
Various species of fish are, however, the most important enemies of the mosquitoes. Great schools of tide-water minnows ([Fig. 93]) are often carried over the low salt-marshes by the extreme high-tides and left in the hundreds of tide pools as the tide recedes. No mosquitoes can breed in a pool thus stocked with these fish. In the fresh-water streams and lakes there are several species of the top-minnows, sticklebacks ([Fig. 94]), etc., that feed voraciously on mosquito larvæ and unless the grass or reeds prevent the fish from getting to all parts of the ponds or lakes very few mosquitoes can breed in places where they are present.