AND FLIES
thorax, the rnouths of which open above the water when the pupa comes in contact with the surface. The pupa, of course, does hot feed, but it is almost as active as the larva, for it rnust avoid its enemies. When disturbed it rapidly swirns downward by quick rnovernents of the abdomen, the extrernity of which is provided with two large swirn- rning flaps. The duration of the pupal stage in midsurnrner is about two days. The adult rnosquito issues flore the pupal skin through a split in the back of the latter. We now see why the pupa
is made lighter than water--it must float at the surface in order to allow the adult to escape into the air. The full-fledged mosquito (Fig. ?74 A) bas the general fea- tures of any other two-winged fly, but it ?s distinguished from nearly all other flies by the presence of scales on its wings and on parts of its head, body, and ap- pendages. The rnouth parts of the adult
/ \ / \_ / \
F?c. 177. ?lëdes atropalpus, male, a mosquito re- lated to the yellow lever mosquito and similar to it in appearance m.osq.uito are of the plerclng and sucking type, and are sirnilar in structure to those of the horsefly, except that the individual pieces are longer and slenderer, and together constitute a beak, or proboscis, extending forward and downward from the head (Fig. I76 A, Prb). The rnale and the fernale rnos- quitoes are readily distinguishable by the character of the antennae, these organs in the rnale being large and feathery (Fig. ?74 B), while those of the female are
[335 ]
" INSECTS
