California Department of Food and Agriculture employees started spraying a pesticide on trees in East San Jose Wednesday to prevent guava fruit flies from damaging fruit crops, officials said.
One worker drove a truck Wednesday morning next to a line of sycamore trees in the 1600 block of Hermocilla Way off of King Road while the passenger sprayed spots of a clear gel onto the trees about 50 feet apart.
The gel contained powerful pheromones meant to attract male flies and a small amount of the pesticide Dibrom to kill them before they breed, said Joe Deviney, commissioner of the Santa Clara County Department of Agriculture and Environmental Management.
"The flies can find it in a snowstorm or on a rainy night," Deviney said. "They'll smell it and go right to it."
The flies use fruit to lay eggs that produce maggots and could cause hundreds of millions of dollars in losses to California's fruit agriculture industry and also affect home fruit growers, Deviney said.
Once the males are killed, the females cannot lay eggs and the insect can become extinct in only about two life cycles, a matter of about two weeks, according to the state Department of Food and Agriculture.
Deviney said the guava fruit fly is from the tropics in Asia and for some reason was transported illegally to Santa Clara County, by plane or some kind of shipment.
California does not have the natural defenses in place that the flies have in Asia, such a competition from other insects and reptiles used to eating them, Deviney said.
"They would love it here," he said.
The spraying by the state agriculture agency will continue for about eight weeks over about 13 square miles, deputy agricultural commissioner Michelle Thom said.
"We caught them really, really early, when the population was low," Thom said. "In a matter of months, we'd have millions of them."
The state learned that the flies were in the county after two were found inside traps in East San Jose about a mile from Wednesday’s spraying site on July 3, said J. Sohal, area manager for the state agriculture department that is supervising the spraying.
State officials contacted the county agriculture department and the two agencies began planning for the eradication effort that started Wednesday, Sohal said.