Oregon’s Department of Agriculture proposes to spray 8,674 acres in North Portland this spring to head off a potential infestation of destructive gypsy moths.

Aerial sprayings tend to cause public scrutiny and worry, however, even when it involves a biological insecticide that’s been successfully used against gypsy moths for more than 30 years. For that reason, the department is hosting a pair of meetings to explain the project. The first is 6:30 to 8:30 p.m., Wednesday, Feb. 17, at James John Elementary School, 7439 N. Charleston Ave. The second is 9 a.m. to noon, Saturday, Feb. 20, also at the elementary school.

Gypsy moths are voracious eaters and multiply rapidly. Unchecked, they could kill trees and or heavily damage Pacific Northwest forests and crops such as Christmas trees. Agencies monitor their presence with traps and spray from time to time to control them.

Two Asian gypsy moths were found in North Portland traps this past summer and another was found across the Columbia River in Washington. Asian gypsy moths are more mobile than the European variety sometimes trapped in the Northwest.

The area proposed for spraying includes Hayden Island, St. Johns, and Forest Park in Portland. ODA proposes three aerial applications in late April and early May, using Bacillus thuringiensis var. kurstaki, commonly known as Btk.

An environmental assessment of the project will be available Feb. 12 from the USDA’s Animal and Plant Health Inspection Service. It can be seen at A comment period ends March 14. Comments should be directed to This email address is being protected from spambots. You need JavaScript enabled to view it. or This email address is being protected from spambots. You need JavaScript enabled to view it..

Btk kills gypsy moths in their caterpillar stage. A publication from Purdue University said the product has several advantages over other means. First, caterpillars killed or sickened by Btk aren’t dangerous to birds or other animals that feed on them. The product breaks down within three to five days after application, so it doesn’t multiply or accumulate in the environment, according to the Purdue bulletin. Btk does not appear to pose a significant threat to humans or pets, according to Purdue.

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