San Bernardino County Medflies Will Be Sprayed : Malathion: Campaign likely will begin May 11.

In a strong indication that malathion-bearing helicopters won’t soon depart the region, state agricultural officials announced Friday their decision to treat a new, 34-square-mile infestation in San Bernardino County with up to eight aerial applications of the pesticide.

The new aerial spraying campaign, tentatively set to begin May 11 over parts of the cities of Highland and San Bernardino, will extend at least through the beginning of July and may require weekly spraying during that period.

Don Henry, deputy director of the eradication project, added that because of the growth of the Medfly infestation it appears that other new Medfly outbreaks may face the same regimen of repeated aerial spraying.

The decision to spray San Bernardino is the first blow to the state’s plan to end repeated malathion spraying by May 9 throughout the Southland and rely on the more benign treatment of releasing millions of sterile fruit flies, used to breed the pest out of existence.

State Department of Food and Agriculture Director Henry J. Voss announced last month that he expected an abundant supply of sterile flies from breeding facilities in Hawaii, allowing an end to multiple spraying in old areas and limiting spraying in newly infested areas to no more than twice.

Voss also announced that no area would have to face the grim prospect of being sprayed once a week “since sterile insects will replace all bait treatments by early May,” according to a March press release.

Voss’ decision, which was made in part to quell the public outcry over malathion spraying, overruled the recommendation of the state’s scientific advisers in the eradication campaign who believed that spraying should not stop in many areas because of concerns that infestation would grow in the spring and there would not be enough sterile flies.

Indeed, over the last month, about 150 more square miles have become infested with the pest and a new breeding facility in Hawaii has experienced production problems, reducing the available supply of sterile flies.

Ed Layaye, San Bernardino agricultural commissioner, said the San Bernardino spray zone probably will have to be treated completely with malathion spraying because of the sterile fly shortage.

Layaye said he expected that the area will have to be sprayed on a weekly basis because hot weather drains malathion’s potency against insects.

Rex Magee, associate director of the state Department of Food and Agriculture, said this week that the unexpected size of the infestation and the potential shortfall in the sterile fly supply has forced the state to reassess if it can safely phase out spraying in previously infested areas.

Voss was unavailable for comment Friday. Magee and Assistant Director Isi Siddiqui, who is in charge of the eradication campaign, were also unavailable for comment.

The latest spraying order brings the total area under malathion treatment to about 470 square miles in Los Angeles, San Bernardino, Orange and Riverside counties.

With the warm weather, which sparks increased breeding by the Medfly, all of the state’s top advisers in the eradication campaign predict that more Medflies will be found through the summer.

The new spray zone in San Bernardino and Highland is roughly bounded by Cajon Boulevard on the west, 9th Street on the south, Palm Avenue on the east and Piedmont Drive on the north.