DNR finds tree-damaging caterpillar in Okanogan area
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DNR finds tree-damaging caterpillar in Okanogan area 

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March 16, 2009

DNR finds tree-damaging caterpillar in Okanogan area
Forest landowners with affected trees asked to participate in control project

OLYMPIA— Forest insect experts at the Washington Department of Natural Resources (DNR) are urging forest and woodlot property owners in Okanogan County to be on the lookout for tree damage from the Douglas-fir tussock moth. DNR has noted tree damage near Palmer Mountain, four miles north of Loomis, and near Chesaw Road, five miles east of Oroville. DNR has launched a project to help control the spread of this insect, which can damage and kill trees, raising the danger of forest fires.

“Tussock moths don’t honor boundaries. All landowners could be affected by this outbreak,” said Commissioner of Public Lands Peter Goldmark. “The long-term health of our forests is key to continue managing the state’s lands sustainably.”

“I encourage forest landowners in the area to look closely for evidence of the tussock moth and contact us to participate in this coordinated effort,” said Glenn Kohler, DNR’s State Entomologist. “Working together, we can minimize the damage.”

In the summer of 2008, DNR aerial surveys detected tree needle damage on about 300 acres of federal and privately owned lands. Follow-up ground surveys found indicators that the infested area was likely to expand during the summer of 2009.

What forest landowners can do
Owners with trees damaged by the Douglas-fir tussock moth are encouraged to participate in a cooperative project to control the spread of this insect. They are asked to contact Glenn Kohler, 360-902-1342, glenn.kohler@dnr.wa.gov.
A combination of careful tree thinning and, where appropriate, the application of biological control methods can reduce tree damage and may prevent an outbreak’s spread. These methods are non-toxic to humans and other animals including most insects. In addition, every effort is made to avoid spraying non-host plants. 

DNR can assist property owners in evaluating their control options, and help coordinate control actions if there is sufficient interest in participation.

Detailed information and images on how to recognize Douglas-fir tussock moth damage is available on DNR’s website. Forest and woodlot property owners should check to be sure they are within the affected area prior to inquiring about assistance. Maps will be distributed to news organizations and are available on the DNR website at:

Tussock Moth Cocoon Female Tussock Moth and Eggmass

Outbreaks affect health of trees and recreation opportunities too

The caterpillar life-stage of the Douglas-fir tussock moth eats the needles of fir and spruce tree species. This moth is native to Washington, and population levels run in cycles, dropping for a period of years between major outbreaks. The last outbreak in the state occurred from 2000 to 2002, leaving at its peak in 2000 more than 45,000 acres of defoliated trees. 

Outbreaks typically collapse within two to three years due to a buildup of natural enemies such as a virus and parasites. However, during an outbreak, up to 40 percent of the trees in an affected area can be killed. Surviving trees may have top-kill—damage to the uppermost foliage on the trees—or may suffer growth loss, or are weakened and more susceptible to other insects, such as bark beetles.

In addition, the hairs of the caterpillars may cause skin irritation in many people, which can limit use of recreational areas during severe outbreaks.

DNR–managing and protecting your natural resources
Administered by Commissioner of Public Lands Peter Goldmark, DNR manages 2.9 million acres of state-owned trust lands, 2.6 million acres of aquatic lands—the bedlands under Puget Sound, the coast, including many beaches, and navigable rivers and natural lakes—and a small but significant 130,000-acre statewide system of Natural Resource Conservation Areas and Natural Area Preserves which protect native ecosystems and the plant and animal species that depend on them. Many also provide access for education and low impact public use.

DNR offers technical assistance and education on a range of subjects, including forest health, forest stewardship, mining, geologic hazards, and rare plant species and ecosystems.
DNR protects about 12.7 million acres of tribal, private, and state lands from wildfire, and is responsible for implementing Forest Practices regulations and regulating surface mining in Washington.

Peter Goldmark is Washington’s 13th Lands Commissioner since statehood in 1889, and the first from Eastern Washington.

Media Contact: Jane Chavey, Senior Communications Manager, 360-902-1721, jane.chavey@dnr.wa.gov 

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Cheri Jarrett
Executive Assistant to Communications Director
Washington State Department of Natural Resources
Fax 360-902-1775


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