State, County Officials Step Up Inspections for Medflies

Examining the cola-colored liquid from the bottom of an insect trap, county agricultural inspector Tony Do found nothing larger than a gnat Wednesday.

That made him happy. He had been looking for the dreaded Mediterranean fruit fly, but he found nothing even resembling the insect’s description--a bug slightly smaller than a housefly, with yellowish-brown wings.

During a routine inspection last Friday, another county expert had found a lone pregnant Medfly in the same trap, which had been sitting in a guava tree at a residence near the intersection of Puente Street and West Walling Avenue in Brea since last summer. The discovery has prompted the state and county to schedule an all-out attack on the fly that will include at least two aerial sprayings of pesticide over a 10-square-mile area beginning next week. The area to be sprayed includes portions of Fullerton, Brea and La Habra.

It was the first--and so far only--fertile Medfly found in Orange County.

However, in Los Angeles County this week, Medflies were found in five additional neighborhoods, officials said Wednesday. The latest discoveries prompted serious doubts there about the current eradication efforts and raised the prospect of widespread aerial pesticide spraying.

The flies were found in South Gate, Monrovia, Eagle Rock, Pasadena and Elysian Park.

In Orange County, Do is one of about 10 inspectors and technicians checking about 350 traps daily to monitor the spread of the fly. In addition, several teams of state officials have been out to sample fruit, looking for Medfly larvae. One wormy piece of fruit was discovered Wednesday, but it has not yet been determined if it contained Medfly larvae.

So far, their inspections have not turned up any new fertile Medflies. Nick Nisson, an Orange County entomologist, said that all the Medflies collected from traps on Tuesday were sterile. Officials said it takes about 24 hours for scientists to determine the sterility, so test results on those flies taken from traps Wednesday won’t be known until today. About 25 sterile flies have been found in Orange County since Friday, he said.

Officials said they have no way of knowing whether the fertile Medfly found in Brea is a “loner” or part of a wider infestation. But Brian Taylor, a state entomologist, said it is likely that the pregnant female had laid eggs, elevating concerns that other fertile Medflies may exist.

“It is always a possibility that it was a loner,” Taylor said. “But in this case it was a mated female, which means she probably had the opportunity to lay other eggs before being trapped.”

When it was confirmed Saturday morning that the fly was fertile, dozens of state and county workers helped place 1,000 traps within an 81-square-mile area, including 789 in Orange County. The new traps were all set by Tuesday.

Before the fly was discovered in Brea, county agricultural officials had checked a few hundred “routine” traps each week, said Steve Hill, the county’s deputy agricultural commissioner. But since the fly was found, they have stepped up their inspections, checking traps daily within a one-square-mile area. They also check traps every other day around an eight-mile buffer to the area.

The county will follow this monitoring routine for one week. If no new flies are found, the department will revert to its weekly schedule, Hill said.

The traps have been placed on many kinds of fruit trees, with the owners’ permission, Hill said. But the flies, who feed on ripe fruit, are more likely to be found in traps on trees that are in season, which now include guava, fig and apple trees.

“Guavas are just in season this time of the year so they are more commonly found,” Do said.

The pregnant fly was found in a McPhail trap, which resembles an upside-down, round sink. The trap lures many types of insects with a liquid called Staley’s mixture, a sweet, brownish mixture of water, yeast and borax. The flies enter the trap through the bottom and eventually drown in the lure.

Inspectors also have been hanging the Jackson trap, which is meant specifically to lure male Medflies. The fly, which is sexually attracted to a special mixture called Trimedlure inside the triangular trap, is captured when it is caught on a piece of sticky cardboard.

Also out on Wednesday were several teams from the state Department of Agriculture’s fruit-cutting detail. The teams go from house to house and carefully inspect garden fruit and vegetables for any sign of Medfly larvae. They often keep their eyes open for near or fully ripened fruit.

“Just before human consumption, the flies like it,” said Genaro Davila, a field supervisor for the detail.

Among the team’s finds on Wednesday was a wormy piece of guava fruit. The fruit, which had fallen from a tree in a yard on Puente Street, contained about a dozen small worms, which were put into an alcohol solution to be tested in a lab. Davila was careful to get all the maggots, which may or may not be Medfly larvae. There are several types of flies that lay eggs in fruit, he said.

Staff writers Steven R. Churm, Stephanie Chavez and Richard Simon contributed to this story.