INSECTS
plants, which they extract by puncturing the plant tissues; they will also feed on the exuding juices of fruit, or on any sort vegetable matter. The females, however, are notorious for their propensity for animal blood, and they by no means limit their quest for this article of food to human beings. The male mosquitoes, apparently, very rarely depart from a vegetarian diet. The pain from the bite of a female mosquito and the subsequent irritation and swelling probably result from the injection of the secretion from the salivary glands of the insect into the wound. It is said that the saliva of the mosquito prevents coagulation of the blood.
Because of the short time necessary for the completion of the life cycle from egg to adult during summer, there are many generations of mosquitoes from spring to fall. The winter is passed both in the adult and in the larval stage. Fertile females may survive cold weather in protected places; and larvae round in large numbers, frozen solid in the ice of ponds, have become active on being thawed out, and capable of development when given a sufficient degree of warmth.
The yellow-fever mosquito, now known as Aëdes aegypti but at the time of the discovery of its relation to yellow lever generally called Stegomyia fasciata, is similar in its habits during the larval and pupal stages to the Culex mosquitoes. It lays its eggs singly, however, and they float unattached on the surface of the water. The adult mosquito may be identified by its decorative markings. On the back of the thorax is a lyrelike design in white on a black ground; the joints of the legs are ringed with white; the black abdomen is conspicuously cross-banded with white on the basal half of each segment. The male has large plumose antennae and long maxillary palpi. The female has a strong beak, but small palpi, and her antennae are of the short-haired form usual with female mosquitoes. The species of Aëdes shown in Figure 177 much resembles the yellow-fever mosquito, but it is a
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