Page:Insects - Their Ways and Means of Living.djvu/399

 AND FLIES

the last segment, in which the posterior spiracles (PSp) are located. The larva floats in a horizontal position just below the surface film of the water (Fig. 18I A), from which it is suspended by a series of floats (,Fig. 178 B, e) consisting of starlike groups of short hairs arranged in pairs along the back. The spreading tips of the hairs pro-

Fç. xSx. Feeding positions of.4n0pheles and Culex mosquito larvae A,/lnopheles larva suspended horizontally beneath the surface film, and feeding at the surface with its head inverted. B, Culex larva hanging from the respira- tory tube

ject slightly above the water surface and keep the larva afloat. In the floating position, the respiratory disc breaks through the surface film, and its raised edges leave a dry area surrounding the spiracles. The long hairs that projéct from the sides of the thorax and the first three body segments are mostly branched and plumose. T'he Anopheles larva (Fig. llqI A) feeds habitually at the top of the water. When disturbed it shoots rapidly across the surface in any direction, but goes downward reluctantly. In order to feed in its horizontal position, it turns its head completely upside down and with its mouth brushes creates a surface current toward its mouth. The pupa of Anopheles (Fig. 179 B) is hot essentially

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INSECTS