Aerial Spray to Be Used in Encino Against Gypsy Moths

A 40-acre area in the Encino hills will be sprayed from the air with a natural bacteria to attack gypsy moths found there last year, state agriculture officials said Tuesday.

A chemical pesticide will also be sprayed from the ground if the Department of Food and Agriculture receives expected federal approval later this week, department spokeswoman Gera Curry said.

The gypsy moth is a voracious eater of tree leaves that defoliated an estimated 2.5 million acres of U. S. forest last year, mostly in the Northeast, state officials said.

Last September, state agriculture inspectors found nine gypsy moths and three “egg masses” in an area near Skytop and Royal Oak roads in Encino. They had inadvertently been brought to California by a family who had moved from Massachusetts.

4 Aerial Sprayings

The plan to combat the gypsy moths includes four aerial sprayings of Bacillus thuringiensis , each two weeks apart, beginning when the caterpillars hatch from their eggs late this month or early next month, Curry said.

The spraying will not be harmful to humans or pets, she said.

The ground treatments will involve two sprayings of trees with the chemical Dimilin on nine properties, Curry said. The federal Environmental Protection Agency is expected to approve the ground treatment part of the plan later this week, she said.

Dimilin kills the caterpillars by preventing them from molting and Bacillus thuringiensis kills them by attacking their digestive system, Curry said.

Many environmentalists prefer bacteria to chemical pesticides because they harm only leaf-eating caterpillars, said Diane Baxter, staff scientist for the Washington-based National Coalition Against the Misuse of Pesticides.

Less Toxic

Baxter said Dimilin is less toxic than some other pesticides and tends to attack few insects other than gypsy moths, but she said scientists are unsure of exactly how long the chemical residue stays on the leaves.

Curry said Dimilin is expected to be applied only twice because it “binds” to the leaves.

She added that the state decided to spray Bacillus thuringiensis from the air instead of Dimilin, which had been recommended for aerial use by a department advisory panel in November, partly because of its successful use in a recent infestation in Oregon.

Curry said that attacking the moths now is imperative because they could become a costly problem if left untreated.

In Oregon, about 400,000 acres infested with the moths were treated with Bacillus thuringiensis in 1985 and 1986 at a cost to the state of about $15 million, said Norma Grier, director of the Northwest Coalition for Alternatives to Pesticides, based in Eugene, Ore. The treatment was successful, she said, reducing the area’s moth population from 19,000 in 1984 to 81 in 1986.

California agriculture officials will hold at least one public meeting later this month to answer residents’ questions about the plan, Curry said.