Encino Spraying of Gypsy Moths Starts Thursday

The spraying of chemical and bacterial pesticides on a small area of Encino to kill off gypsy moths is scheduled to begin this week, state agriculture officials said Monday.

The state Department of Food and Agriculture had announced the treatment plan last month in response to the discovery last September of the moths, whose larvae strip trees of their leaves, in the lush hillside area.

Nine properties near Skytop and Royal Oak roads are scheduled to be sprayed on the ground Thursday and April 2 with the chemical Dimilin, which kills the young caterpillars by preventing them from molting, department spokeswoman Gera Curry said.

Foliage unreachable by ground crews will be sprayed by helicopter with the biological insecticide known as Bacillus thuringiensis, or “B.t.” The bacteria paralyzes the digestive system of a caterpillar, causing it to starve to death.

The aerial B.t. spraying of a 40-acre area surrounding and including the nine properties is set to begin just after dawn Saturday, Curry said. The bacteria is to be sprayed from the air three more times in the next two months, with the sprayings two weeks apart, she said.

Rain or a threat of rain would delay the spraying of either insecticide.

The pesticides have a “very minimal” effect on beneficial insects, and neither is harmful to humans or pets, Curry said.

By Wednesday, agriculture officials hope to have finished notifying residents in person and by phone, she said. In all, 41 property owners will be affected.

State agricultural scientists decided to begin their efforts now because caterpillars are starting to emerge in force from egg masses that were found in Encino last year and which have been monitored in a laboratory. If allowed to survive, each caterpillar would feed for about 10 weeks, grow to 2 1/2 inches, and eat as many as seven leaves a day, Curry said.

“Now is the best time to eradicate them because they’re so voracious,” she said.