The third discovery of oriental fruit flies in Santa Clara County this year has prompted a treatment in San Jose and Monte Sereno that will last for eight weeks, a county official said Friday.
Two oriental fruit flies were found on Sept. 22 and 23 on Westmont Avenue, north of state Highway 85 in San Jose and Karl Avenue, and west of Vasona Reservoir in Monte Sereno, county Agricultural Commissioner Joseph Deviney said.
The two trapped flies prompted an emergency proclamation for an immediate eradication program by the state secretary of agriculture, county officials said.
The insects were sent to the state Department of Food and Agriculture where they were confirmed to be oriental fruit flies, Deviney said.
The treatment started Thursday and will continue every two weeks through November, during which time a crew from the state agriculture department will apply a clay-like gel at about 8 to 10 feet high on fruit trees and utility poles, Deviney said.
The gel consists of a pheromone intended to attract male flies and a small amount of insecticide, he said.
After the eight-week span, when the oriental fruit fly population is expected to collapse, the county will continue to use its sticky cardboard traps to catch and detect the flies, according to Deviney.
The treatment area covers 15 square miles roughly bordered by Prospect Road and Hamilton Avenue to the north; San Tomas Expressway and White Oaks Road to the east; Los Gatos Boulevard and Wood Road to the South and Fruitvale Avenue to the west.
There has been an unusual increase this year in oriental fruit fly infestations in Southern California and the Bay Area, Deviney said, adding that there was only one infestation in Santa Clara County last year.
This year, six oriental fruit flies were found in Cupertino and two in Los Altos Hills, according to Deviney.
Oriental fruit flies come from tropical regions in Southeast Asia and have moved to Hawaii, according to Deviney.
"This is an insect we don't have and doesn't belong here," he said.
The flies have faster reproductive cycles due to the warmer climates they are accustomed to. They are known to lay their eggs on 230 different fruits and vegetables, according to Deviney.
During the summer months it can take about a month for an egg to fully develop, he said.
Deviney suspects the insects are coming from illegal shipments and recommends people who are traveling from foreign countries make sure they don't come back with any "hitchhiking" flies.