3 Medfly Finds May Mean Far Worse Problem Than Thought

The discovery of Mediterranean fruit flies in Glendora, San Dimas and the city of San Bernardino was announced Tuesday by baffled state experts, who in past weeks have seen Southern California’s worst Medfly infestation explode inexplicably in the region’s eastward sectors.

All three of the flies, which typically represent thousands of wild Medflies not detected by the state’s admittedly leaky trapping network, were found Monday in residential neighborhoods.

Immature female flies were found in the previously uninfested sections of Glendora and San Dimas in the eastern San Gabriel Valley. No decision has been made on whether to treat the areas with aerial malathion spraying.

In San Bernardino, a single immature female Medfly was trapped eight miles from where another Medfly was trapped April 4.

Roy Cunningham, chairman of the state Medfly Science Advisory Panel, said the two San Bernardino discoveries mark a disquieting development in the 9-month-old infestation, indicating that the problem may be much larger than previously suspected.

Cunningham, widely regarded as one of the most conservative and knowledgeable of the expert advisers, said he believes the discoveries will probably trigger the beginning of aerial malathion spraying over much of the northern part of San Bernardino.

Until this year, only one Medfly had ever been found in either San Bernardino or Riverside counties. In the past month, five have been trapped, from Upland, near the Los Angeles County line, to the agricultural community of Woodcrest in Riverside County.

“I don’t know what is coming off,” Cunningham said. “Why are they way out there and scattered all over? I don’t know what the deal is.”

State agriculture officials have made no decision on what action to take, although intensive trapping already has begun in San Bernardino to better determine the extent of the infestation.

Pat Minyard, deputy manager of the eradication project, said that despite the number of new flies found, the discoveries would have no effect on the state’s plan to phase out aerial spraying in already infested areas. The spray program is to be supplanted by the release of sterile flies, which are supposed to breed the pest out of existence.

“We’re still OK,” Minyard said. “Sterile flies are a limited resource, but for the time being we will continue to march with that plan.”

Cunningham said he expects the five entomologists who serve on the advisory panel to make a strategy recommendation in the next few weeks. The scientists have found themselves linked in emergency telephone conferences with increasing frequency since late March as the number of fly discoveries has boomed.

On Monday, the science panel recommended that aerial spraying begin in Woodcrest, Walnut and a part of Los Angeles south of Hancock Park.

State Department of Food and Agriculture Director Henry J. Voss approved aerial spraying over 19 square miles in Woodcrest, but no decision was announced Tuesday on the recommendations for Walnut and Los Angeles.

The latest San Bernardino find could force a significant expansion of spray zones that already encompass more than 400 square miles.

Cunningham said that because the two Medflies discovered in San Bernardino were separated by eight miles, they conceivably could be considered separate infestations that would not necessarily require malathion spraying. But he said his opinion is that the two discoveries should be linked and spraying ordered for the entire area around and between them.

“Logically, these are not separate finds, but part of something bigger that we haven’t figured out yet,” he said.

Cunningham said the discoveries were particularly disturbing because they come early in the year before the pest’s most prolific breeding period in the hot summer months.

“The critical point is what it is going to be like at the end of June,” he said. “Every week we seem to get more bad news.”

MEDFLY SPRAYING MAP: B2