Expansion of Medfly Spraying Zone Set : Agriculture: Parts of Rowland Heights, Diamond Bar and Industry will get aerial applications of malathion. Two of the pests have been found in the area recently.

The state’s aerial spraying campaign against the Mediterranean fruit fly spread Thursday to previously untouched portions of northeast Los Angeles County after the discovery of a Medfly in a loquat tree.

The immature female fly was trapped Tuesday in residential Rowland Heights, slightly more than a mile away from where another fly was found 2 1/2 weeks ago in neighboring Diamond Bar.

Agriculture officials announced Thursday that a 16-square-mile sector encompassing parts of Rowland Heights, Diamond Bar and Industry will be sprayed twice with the pesticide malathion beginning at 10 p.m. next Wednesday. The sprayings will be followed in early May with the release of millions of sterile Medflies, used to breed the pest out of existence.

The new aerial campaign marks the first expansion of the spray zone since February and comes just as state agriculture officials are preparing to phase out aerial spraying in 366 square miles of Los Angeles and Orange counties by May 9.

Rex Magee, associate director of the state Department of Food and Agriculture, said the new spray zone will not affect the May 9 deadline.

“This won’t change the deadline or anything else,” he said.

But some of the state’s own scientific advisers are skeptical that the deadline can be met. “I’ve always felt May 9 was extremely, absolutely premature,” said Richard Rice, a UC Davis entomologist and one of five scientists on the state’s Medfly Science Advisory Panel. “This is the first of probably many finds. I hope that date isn’t locked in concrete.”

UC Davis entomologist James R. Carey, another member of the panel, said he believes the two Medflies found in Rowland Heights and Diamond Bar are only the beginning of a spring resurgence of the pest.

Carey said the vast majority of Medflies detected over the last 15 years have been found in late summer and early autumn, when the temperature and the availability of fruit both peak.

He said the discovery of a Medfly in Rowland Heights confirms his fear that the war against the pest, which began last July with the discovery of a single fly near Dodger Stadium, has only started.

“They’re in deep trouble,” Carey said. “This is just the beginning.”

Word that aerial spraying will soon start in the three communities, located about 20 miles east of Los Angeles in the San Gabriel Valley, sparked a strong reaction from local officials, who have watched with increasing anxiety as the state’s spraying campaign worked its way around their borders.

Diamond Bar Councilman Paul Horcher said he was prepared for the announcement about the start of aerial spraying, but still found it upsetting.

“I’m getting sick of it all. I think the whole valley is,” Horcher said. “It’s clear the citizens here are being used as backstops for mistakes the agriculture people have been making. We thought this was wrapping up. I guess not.”

Councilman Gary Werner said the announcement of spraying was a frustrating development because of the state’s apparent inability to control the spread of the pest.

Werner was the sponsor of a Diamond Bar City Council resolution last month opposing aerial spraying over its territory. The resolution was largely symbolic since the city has no authority to stop the state’s eradication program.

“It doesn’t seem like there’s anything we can do about it at this point,” Werner said.

Magee said the new spray zone will have top priority in receiving the increased shipments of sterile flies expected in late April. The balance of the sterile flies will be used to phase out aerial spraying in previously infested areas.

Science panel members have expressed concern that each new infestation will deplete the sterile flies needed to phase out sectors already being sprayed. The panel has recommended that spraying in those areas continue rather than be disrupted by shifting to the use of sterile flies when eradication is close.

Magee countered that the state expects to have more than enough flies to phase out areas now being sprayed and handle new outbreaks.

“It’s going to take two or three more (infestations) before I start getting nervous,” Magee said.

The new spray zone is roughly bounded by Valley Boulevard on the north, Nogales Street on the west, the Diamond Bar city limits on the south and Derringer Lane on the east.

MEDFLY SPRAYING MAP: B2