First Batch of Sterile Medflies Released

Four million sterile male Mediterranean fruit flies were released Tuesday, launching a massive birth-control program aimed at wiping out the crop-destroying pest in the San Fernando Valley, agriculture officials said.

In the next two months, state agriculture officials expect to release 100 million to 300 million of the sterile male Medflies to induce the insects to “breed themselves out of existence,” said E. Leon Spaugy, Los Angeles County agricultural commissioner.

“We will overwhelm the native population,” Spaugy said after lifting a cardboard bucket from a picnic table and letting a sample of 4,500 insects loose at a press conference Tuesday at Louise Park in Van Nuys.

“These guys are promiscuous” and will mate with as many females as possible, decreasing the chances that females will find fertile males to mate with, said Thomas Palmer, coordinator of the eradication project for the state Department of Food and Agriculture.

Roving Truck

Earlier Tuesday, crews on a truck turned loose two million sterile male Medflies in similar fashion over 28 square miles of the West Valley. Another two million Medflies were released from an airplane over 62 square miles. About 20 million sterile flies in all will be released this week, with that number increasing to as many as 40 million each week for the next two months, Spaugy said.

The sterile flies are dyed pink so that if caught in one of the state’s traps, they can be distinguished from Medflies already in the area, Spaugy said.

The sterile fly release is the second step of an eradication program that began last week with the aerial spraying of the pesticide malathion over 16 square miles in the Northridge-Reseda area, where the first Medflies were discovered July 20. In all, six Medflies--three males and three females--have been found in the state’s traps.

Female Medflies lay their eggs in more than 250 different types of produce. When the eggs hatch, the insect larvae render the fruit or vegetables inedible and unsalable.

The sterile insects are expected to head off a need for more aerial malathion spraying, despite the discovery of two immature male Medflies last weekend in a Reseda yard, Spaugy said. The yard was sprayed with malathion.

If Medflies are found outside the area where the sterile flies are being released, more aerial spraying might be necessary, especially if the finds are mature, mated females, he said.

Release Area

The sterile fly release area corresponds roughly to the 62 square miles quarantined last week by the state Department of Food and Agriculture. Residents are not allowed to remove home-grown fruit from the quarantine area, which has a jagged boundary defined roughly by the Santa Susana Mountains on the north, De Soto and Corbin avenues on the west, the Ventura Freeway and Victory Boulevard on the south and Woodman Avenue on the east.

The cost of the eradication effort is expected to be “in the neighborhood” of the $2 million spent last year on an infestation in East Los Angeles, Spaugy said.

The infestation is expected to be eliminated and the quarantine called off by early November, Palmer said.