Wasp v. Weevil

Smartest way for man to fight the insects who rival him for the earth's bounty is to turn insect against insect. The wasp Microbracon mellitor assassinates boll weevils (which last year destroyed 12-14% of the South's cotton), so this week an army of these stiletto-bearing flyers is being propagated at the University of Texas.* The Texas wasp dashes among cotton rows, seeks out bolls full of weevil larvae, plunges her stiletto into each grub, forces an egg through the hollow tube into each paralyzed victim, then flits on to another boll. In two days the wasp egg hatches into a grub which lives off the juices of the weevil grub until it is fully grown in five days. It lives about 30 days, matures and in turn deposits 45 eggs which kill a like number of weevils. About 400 female wasps per acre will clean up badly weeviled fields.

In 1899 Frederick W. Malley of Texas discovered that this wasp, a U.S. native, was a weevil parasite. In 1938, the Clayton Foundation, founded by famed Cotton-man Benjamin Clayton, put scientists to work on the wasps' use. Directed by Botanist Glenn W. Goldsmith, young Entomologist John M. Carpenter studied the insect, announced last week that it can be propagated in honey-smeared cages, released in fields to work as effectively as the unpampered outdoor variety. He is now devising equipment for mass production of the billions of wasps which cotton growers need.

*Federal bugmen in New Jersey have loosed swarms of another wasp, Tiphia, together with a bacterium, against the Japanese beetle (TIME, April 28).

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