. Fresh-water biology. Freshwater biology. AQUATIC INSECTS 911 in the scum and about the edges of all sorts of fresh water, while their adults swarm in thickets about the shores of pools. The Ptychopteridae inhabit swales, their larvae hving in the rotting trash at the edge of the water, and the adults fluttering about the tops of the adjacent herbage. The dixa midges (Dixidae) inhabit spring brooks and clear pools, and their larvae (Fig. 1379), with bodies bent double, slide out upon the surfaces of wet leaves and stones, or edge off into the water and whirl about in short curves; the adults
. Fresh-water biology. Freshwater biology. AQUATIC INSECTS 911 in the scum and about the edges of all sorts of fresh water, while their adults swarm in thickets about the shores of pools. The Ptychopteridae inhabit swales, their larvae hving in the rotting trash at the edge of the water, and the adults fluttering about the tops of the adjacent herbage. The dixa midges (Dixidae) inhabit spring brooks and clear pools, and their larvae (Fig. 1379), with bodies bent double, slide out upon the surfaces of wet leaves and stones, or edge off into the water and whirl about in short curves; the adults dance in companies above the surface of the water. Some larvae of the Rhyphidae hkewise inhabit pools, and the adults sometimes assemble and dance in the shelter of forest trees at some dis- tance from the water. The few known aquatic members of the Leptidae live as larvae in streams and cling with the well- developed claws of their stout muscular '^J^ abdominal prolegs' to the surfaces of stones; the adults flit about the shore, ,79. Larva (j?) and pupa (5) of J. 1 . ,1 . n 11 the dixa-midge. (After Tohannsen.) displaying their unusually gaudy colors and velvety textures. These are small and comparatively un- important families. Then there are a few large famihes of which but a small proportion of the members are adapted to aquatic hfe. The crane-flies (Tipu- lidae) are essentially terrestrial: most of them live in moist earth or wet leaves. Some are strictly amphibious, like Epiphragma (Figs. 1380 and 1381). They possess as larvae the usual terminal spira- cles for breathing air, but have these set upon a respiratory disc that can be closed by folding together on the middle line, and they have a bundle of four anal gills that may then be protruded for use under water. There is a fine development of fringes about the respiratory disc of other species, and these fringes spread out upon the surface film, holding the spiracles up to the air, while the larvae are moving about
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectfreshwa, bookyear1918
