Science: Sex and the Screwworm

Hatched in open sores on cattle, their screw-shaped larvae can literally eat their way through a live steer. For years, they were a major scourge of the cattle country in the U.S. Southwest. It was not until the 1960s that screwworm flies were brought under control by a cunning form of biological warfare. Millions of flies, bred in a factory in Mission, Texas, were irradiated with sterilizing doses of gamma rays and released into the wild. When sterile males mated with normal females, which make only one sexual contact during their two or three...

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