Page:Insects - Their Ways and Means of Living.djvu/410



adult behavior, are, however, most obnoxious creatures during their larval stages. The ordinary blowflies, which are related to the house fly, lay their eggs in the bodies of dead animals, where the larvae speedily hatch and feed on the putrefying flesh. Another kind of blowfly deposits living larvae instead of eggs. These flies may be regarded as beneficial in that their larvae are scavengers. But some of their relations appear to have taken a diabolical hint from their habits, for they make a practice of depositing their eggs in open wounds, sores, or in the nostrils of living animals, including man. The larvae burrow into the tis- sues of the victims and cause extreme annoyance, suffer- ing, and even death. A notable species of this class of pests is the screw worm. Infestation by fly larvae, or maggots, is called myiasis. Well-known cases of animal myiasis are that of the bot- fly in horses and of the ox warble in cattle. The flies of both these species lay their eggs on the outside of the animals. The young larvae of the botfly are licked off and swallowed, and then live until full-grown in the stomach of the host. The young ox-warble larva burrows into the flesh of its host and lives in the body tissues until mature, when it bores through the skin on the back of the afflicted beast, drops out, and completes its transforma- tion in the ground. Not only animals but plants as well are subject to in- ternal parasitism by fly larvae. Garden crops are at- tacked by leaf maggots and root maggots; orchardists in the northern States have to contend against the apple maggot, which is a relation of the olive fly of southern Europe and of the destructive fruit files of tropical coun- tries. That notorious scourge of wheat fields, the Hessian fly, is a second or third cousin of the mosquito, and it is in its larva form that it makes all the trouble. The special attention that bas been given to pestiferous files must make it appear that the Diptera are a most undesirable order of insects. As a matter of fact, however,

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MOSQUITOES