Asian gypsy moth makes appearance in Portland

East Coast forest defoliation caused by EGM
East Coast forest defoliation caused by EGM

In 2015, Asian gypsy moths (AGM), a plant-eating invasive species, were detected in Portland’s Forest Park and northern part of the St Johns neighborhood. The moths were found during routine monitoring in traps placed throughout the region by the Oregon Department of Agriculture. A related species, the European gypsy moth (EGM), was also found. EGM is endemic to the northeastern United States, has defoliated millions of acres of trees and shrubs, and since the late 1970s, small isolated populations have been detected and eradicated in Oregon. AGM represent an even greater threat, however, because unlike EGM females, AGM females fly and are attracted to city lights.

But not only are AGM more invasive than EGM, AGM also feed on a wider range of host trees, including conifers such as larch that are not favored by EGM. Preferred broad-leaf hosts include oak, apple, alder, aspen, filbert, willow, birch, madrone, cottonwood, and plum. Coniferous species such as Douglas fir, pine, and western hemlock are suitable hosts as well. Reading this list, it is not hard to imagine the environmental and economic havoc that gypsy moths could inflict on the Pacific Northwest. Establishment of gypsy moth threatens forest ecosystems and results in long-term increases in the use of pesticides by homeowners as well as by forest and nursery managers.

Gypsy moth male
Gypsy moth male

An AGM eradication program in Northwest Portland is being planned for the spring of 2016.  The recommended strategy includes aerial application of a minimal-risk biological insecticide approved for use on organic food crops to routinely control caterpillar pests, with the active ingredient Bacillus thuringiensis var. kurstaki (Btk). Btk is a naturally occurring bacterium that has been used effectively in other gypsy moth eradication projects in Oregon since 1984. The U.S. Department of Agriculture is currently conducting an environmental assessment through the National Environmental Policy Act to review this recommendation. The environmental assessment requires that the public be provided a 30-day period to comment on its findings. It is expected this document will be available for public comment in early February.

Two public open-house events, coordinated by the Oregon Department of Agriculture and the Oregon Invasive Species Council, will be held to discuss the Asian gypsy moth eradication program. The goals of these events are to share information about the Asian gypsy moth, discuss the eradication proposal, and answer questions. Governmental and non-governmental agencies will be on hand. The events will be held at James John Elementary School, 7439 N. Charleston Ave, Portland, OR 97203. The first is February 17, 2016 from 6:30 pm to 8:30 pm & February 20, 2016 from 9:00 am to 12:00 pm.

For more information about gypsy moths:

Asian versus European gypsy moth

1992 Asian gypsy moth eradication program

APHIS fact sheet

Gypsy moth in Oregon – 2015

Oregon Invasive Species Council information

For information on Btk:

From Oregon Public Health

National Pesticide Information Center fact sheet

General questions about Bt (NPIC)

On YouTube (NPIC)

From Purdue University

CalEPA fact sheet

Seattle & King County fact sheet