Blow fly is the name of several kinds of flies. Many have bodies colored a metallic blue or green. Because of their appearance, some of these flies are called bluebottles or greenbottles. Some blow flies are the size of the house fly, and others are three or four times larger. Their eggs are laid in meat, in the bodies of dead animals, or in wounds of living ones. Dead meat or living tissue in which the eggs have been laid is said to be flyblown. The eggs quickly hatch into wormlike maggots which tunnel through the flesh. Blow fly maggots may cause disease in people and animals. They should be kept out of houses, and great care should be used to keep all food out of their reach. Garbage cans should be tightly covered, because blow flies breed in them. These flies may produce thousands of offspring in a few days.
Some blow fly maggots, such as screwworms and wool maggots, eat the body tissue of living animals. The eggs are laid in open sores in the hides of livestock. The infestation of fly maggots in the flesh of live animals is called myiasis. When they feed in large numbers, blow fly maggots may cause death to farm animals. One method of controlling these flies is to sterilize male flies by radiation. Females that mate with these males lay eggs that will not develop.
Blow flies do good as well as harm. They dispose of the bodies of dead animals that would otherwise take a long time to decay. Some blow flies pollinate plants.
