S.D. May Get Aerial Dose of Malathion : Mexfly: Discovery of the pests, which can cause havoc with crops, could result in spraying of chemical from the air for the first time in the county.

Three Mexican fruit flies have been trapped in El Cajon and state officials are considering the first aerial spraying of malathion in San Diego County, state and county officials confirmed Wednesday.

The Science Advisory Panel of the state Department of Food and Agriculture was briefed by telephone Wednesday about the recent Mexfly finds--one mature male and two egg-bearing mature females that have been trapped since April 25 in a residential area just south of Interstate 8.

The advisory panel, which helps guide statewide response to the fruit fly problem, is expected to make its recommendation to the state director of Food and Agriculture today, according to Gary Reece, chief of agricultural services for the San Diego County Department of Agriculture, Weights and Measures.

“Ground treatment or aerial treatment of malathion I’m sure is being discussed,” Reece said. “There’s strong reason to believe that an infestation has started. I know they’re going to be interested in doing whatever they feel is needed to keep it from getting out of hand.”

Dianne Jacob, administrative assistant to Supervisor George F. Bailey, said Bailey’s office has been kept apprised of the state’s deliberations about how to address the Mexfly problem.

“I’m waiting for a report of what the action plan is going to be at this point,” she said. “Whether or not they’ll be spraying (malathion), we don’t know yet. It is a possibility.”

Mexican fruit flies are considered “the next major pest” after the Mediterranean fruit fly, or Medfly, according to Dr. Isi Siddiqui, assistant director of the state Department of Food and Agriculture. Slightly larger than house flies, the yellowish brown, banded pests are particularly dangerous to citrus, avocados, peaches, pears and other subtropical fruit.

The last major local infestation of Mexflies, which spoil fruit by burrowing inside it to lay their eggs, occurred in 1954 in San Ysidro. Since then, isolated finds have been fairly frequent, and scientists speculate that the flies may hitch a ride across the Mexican border on fruit carried by tourists.

This week, the state began a voluntary malathion ground-spraying program on El Cajon properties within 200 yards of where the Mexflies were found. On Tuesday and Wednesday, 19 property owners agreed to the spraying, according to Marty Muschinske, a state economic entomologist based in San Diego.

“At this point it is voluntary, but once a statement of decision is made it will probably become mandatory,” Muschinske said, adding that aerial application of malathion is possible.

According to Siddiqui, what is significant about the recent trappings is not the number of Mexflies found, but that they were one-third of a mile apart.

“The Mexican fruit fly in San Diego County, because of the proximity (to the border), are not unknown,” he said. “Last year, there were nine single Mexfly finds there. But, finding three flies, especially two mated females, is cause for concern.”

Reece agreed. “If you trap multiple flies in a close proximity, then you know you have more flies there,” he said, adding that the county routinely maintains 2,700 traps--five traps per square mile--that are monitored year-round. When a fly is found, the county steps up its program to 80 traps per square mile, as was done in late April in El Cajon.

Soon afterward, on May 4, a fourth Mexfly was trapped more than 15 miles away, just north of Balboa Park. But scientists said the mature but unmated female was not cause for immediate concern because it appeared to be an isolated case.

County and state officials agree that, even if malathion spraying is ordered, the use of sterile Mexflies will probably still play a major part in the pest-eradication strategy. The U.S. Department of Agriculture, in conjunction with its Mexican counterpart, has a continuing program to release a curtain of sterile fruit flies south of the border to help prevent the spread of the flies.

Reece and Muschinske said they believe San Diego County may begin releasing sterile flies as well, and Jacobs said Bailey’s office had been consulted about where breeding facilities can be placed in the community.

“Whatever is done needs to be done quite quickly,” Reece said, pointing out that because the program generally requires about a million flies per square mile, the breeding of flies needs to begin immediately. “If they decide to use the sterile release program. . . . that requires lead time.”

During the past several months, Los Angeles County has trapped “several” Mexflies, including three in one day in one trap, according to Bill Edwards, Los Angeles County’s chief deputy commissioner of agriculture. But all of the Mexflies were trapped in areas already being treated for Mediterranean fruit flies “so we haven’t had to do anything special,” Edwards said.