You can join the search for beetles that threaten Washington trees

Washington state property owners and people with swimming pools are being urged to become part of a defensive initiative to protect trees from invasive beetles.

August is National Tree Check Month, and at least four state agencies are asking tree owners this month to take a 10-minute walk around their property to look for insects that don’t belong in our region.

Nationwide, more than a third of all insect invasions are first detected by average people, according to Justin Bush, executive coordinator of the Washington Invasive Species Council. Heading off an invasion before it gets started could save untold millions of dollars worth of trees, as well as the costs of battling a spreading insect invasion.

Citrus longhorned beetle
Photo: USDA Plant Protection Service, Bugwood.org

This is the second year that Washington state agencies are bringing the message home from other states where many longtime tree populations have been decimated by insects, including the citrus longhorned beetle and the emerald ash borer.

“While we don’t have these two invasive insects right now, we could get them at any moment,” Justin told me. “We want people to help us look for them.”

This year, state officials also are asking people who own swimming pools and ponds to join in the defensive effort, as some of invasive insects end up in the water and die. A swimming pool owner or maintenance person should take note of any unusual insects found in pool filters or among debris skimmed off the surface of the water, he said. On the East Coast, swimming pool owners are often able to spot invasive beetles even before they show up in traps designed to attract them.

It would be helpful if people would look for invasive insects all year long, Justin said, but August is a good time to place a special emphasis on the effort, because this is the time that most wood-boring insects emerge as adults.

Emerald ash borer
Photo: Debbie Miller, U.S. Forest Service, Bugwood.org

Identifying specific species of beetles is often difficult, Justin acknowledged. The best advice is to take pictures of the insect from several angles and send the photos to the Invasive Species Council, InvasiveSpecies@rco.wa.gov, which will find an expert to identify the bug.

People shouldn’t hesitate to send photos, Justin said. “If it comes to us, we can figure it out.”

Another reporting method is to download the “WA Invasives” app to send photos and location data straight from your smart phone. See WISC download page. The app also includes photos and information for identifying invasive species.

When emailing, one should include contact information, including a phone number, along with the location of the insect sighting. (An address or cross-street description would be helpful.) Details about the tree species should be included as well.

If you obtain one of the beetles, you should keep it in case an expert wants to inspect the specimen. Another option is to take the beetle to a local office of WSU Extension, which can forward it to appropriate experts.

The citrus longhorned beetle, a close relative of the disastrous Asian longhorned beetle, is a major concern on the West Coast. The beetle can feed on a variety of hardwood trees, including apple, maple, oak, willow, alder and popular. When they emerge, they leave an exit hole about 5/8-inch in diameter in the tree.

In 2001, the citrus longhorned beetle was found in Tukwila, where it arrived in a shipment of bonsai trees. Three beetles were recovered from the bonsai trees but five others were seen flying away. Nearly 1,000 trees were cut and chipped within one-eighth mile from the location site, and another 1,500 trees farther away were treated with insecticide. The last beetle was seen in the fall of 2002, and a quarantine remained in effect until 2006. See U.S. Department of Agriculture website.

Because of heavy shipping from Asian ports, concerns remain high that damaging beetles will be imported to the West Coast, Justin said. Insects could also arrive from infested areas back East, which is the primary route for European gypsy moths brought into Washington state in moving vans. This state’s gypsy moth eradication program — including nearly 100 local battles since 1979 (PDF 307 kb) — has kept the damaging moths from establishing a permanent foothold in this state.

Besides the citrus longhorned beetle, officials are concerned that the emerald ash borer could devastate ash trees in this state. The exit holes in ash trees are about a quarter-inch in diameter and have a distinctive “D” shape. Ash trees are common in urban areas, and the beetles apparently have been moving westward as campers bring firewood from eastern areas. The beetle was recently discovered in Boulder, Colo.

State agencies involved in the effort to track down the invasive beetles are the Invasive Species Council, Department of Agriculture, Department of Natural Resources and Washington State University Extension.

The U.S. Department of Agriculture offers information on these and other invasive insects:

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