GAINESVILLE, Fla. (AP) _ A red-eyed Brazilian fly was turned loose Friday in an experimental effort to control the mole cricket, which chews up $47 million worth of crops and lawns each year.

The first release of 250 fly pupae in an Alachua County pasture will probably be followed by others throughout the summer, said Howard Frank, director of the project at the University of Florida's Institute of Food and Agricultural Sciences.

''We're optimistic, but the whole thing is a big experiment,'' said Frank.

The mole cricket, which probably arrived by ship from South America, damages vegetation by tunneling through it.

The pest is now spreading into Georgia, Alabama and South Carolina, Frank said

The Brazilian fly, about the size of a house fly, comes to the mating call of male mole crickets, and lays her living larvae on or near the singer. The larvae then burrow into the male and his mates.

Ten days later the mole cricket is dead, said Tom Walker, the IFAS entomologist who will monitor the progress of the Brazilian fly.

''We should know in a year if the larvae are surviving,'' said Frank. ''And in two years we'll have a reasonable idea of whether it's a success.''

The U.S. Department of Agriculture granted permission to release the flies after laboratory tests demonstrated they only attack mole crickets.

The fly is the third biocontrol agent that IFAS has unleashed in Florida against mole crickets.

A wasp that subdues mole crickets but does not sting people was the first. Turned loose in 1981 near Fort Lauderdale, the colony is holding its own there. They mainly attack a tropical mole cricket that is only a pest in South Florida, however.

Nematodes, microscopic worms, were released in 1985 and 1986 in several Alachua pastures. Offspring are still there and seem to have caused a decline in mole cricket populations at the release sites, but Frank says the nematodes are harder to handle than the Brazilian fly.