OLYMPIA – Several state agencies are urging the public to take ten minutes this month to check trees in their communities for signs of invasive insects. The Washington Invasive Species Council, Washington State Department of Natural Resources Urban and Community Forestry Program, Washington State Department of Agriculture, and Washington State University Extension join forces each August to request public assistance in spotting invasive wood-boring insects and the damage they cause in trees. Late summer is the peak time for these invasive insects to emerge in their adult stage.
In addition to appearing in trees, invasive insects can be found in lights and standing water, such as dog bowls and birdbaths. Pool filters may also trap invasive insects. “Researchers and scientists are monitoring for invasive species statewide, but we need the public’s help,” said Stephanie Helms, executive coordinator of the Washington Invasive Species Council. “Public awareness of emerging invasive pest issues can greatly reduce the risk of spread, as human travel plays a major role in the movement of unwanted insects.”
According to a state study, at least seventy new insect species have been detected in Washington since 1990, with the public discovering 36 percent of these new insects first. This highlights the importance of an educated and aware public. “While you are outside enjoying the summer, take ten minutes to search your yards and neighborhood trees,” suggested Zeima Kassahun of the Washington Department of Natural Resources. “If you see or suspect you see an invasive insect, report your findings, including a picture, to the Washington Invasives mobile app or on the Washington Invasive Species Council website, which routes the report to organizations that can help.”
Initial signs of invasive insect damage to trees include sudden dieback or death among otherwise vigorous and healthy trees. Residents should investigate further if they observe sawdust, exit holes, or adult beetles. The invasive pests of particular interest include the Invasive Longhorned Beetles, which have larvae that feed on and in the wood of trees. When the beetle becomes an adult, it emerges through holes, further weakening the tree. These beetles are highly destructive to hardwood trees. Although not currently established in Washington, they have been found and swiftly stopped multiple times in the past, preventing potentially millions of dollars in damages and saving countless trees. Invasive longhorned beetles can be mistaken for native lookalikes, such as the banded alder borer and spotted pine sawyer, which are beneficial to Washington’s forests.
Another pest is the Emerald Ash Borer, a small, wood-boring beetle that attacks and kills ash trees. The larvae burrow under the tree’s bark and consume the sapwood, which can no longer transport water and nutrients, causing the tree to die gradually. Although not yet in Washington, it was detected outside Portland, Oregon in 2022 and most recently in Vancouver, British Columbia in 2024. The Spotted Lanternfly, a piercing, sucking insect that feeds on sap from various trees, including apples, cherries, grapes, plums, walnuts, and hops, is another concern. While not yet found in Washington, the lanternfly has been intercepted in California as a hitchhiker on goods coming from the eastern United States, where it is established.
To participate, search trees, outdoor light fixtures, outdoor equipment, and standing water for signs of invasive insects. If a suspected invasive insect is found alive, take a photograph and submit a report with details to the Washington Invasive Species Council through the mobile app or website. If a suspected invasive insect is found dead in lamps, pools, etc., collect and place the insect onto a white background (such as a paper plate, piece of paper, or paper towel). Photograph the insect from multiple angles (top, side, etc.), ensuring the photo is in focus. Place the insect into a zip-top bag or sealable container for safe storage. Entomologists may ask you to mail the specimen to a lab for identification. Report the sighting to the Washington Invasive Species Council mobile app or website, and repeat as often as you find a suspicious insect.
For those uncomfortable with handling insects, participation in August Tree Check Month can still be done by taking actions to prevent the spread of unwanted pests. Don’t move firewood; buy firewood where you’ll burn it or gather it on-site when permitted. Moving firewood may transport invasive insects hiding within. Also, don’t move a pest; when traveling locally or moving to a new area, check your bags, outdoor gear, and boxes to ensure they are insect-free. Invasive insects, in any life stage from egg to adult, can easily hitchhike in bags, equipment, and boxes, as well as on items stored outside or in your garage.
“Alert residents can help spot infestations when they are easy to handle,” said Helms. “All it takes is ten minutes to check your trees this August, and you could save the state hundreds of thousands, if not millions, in potential invasive species management costs. And yours could be the report that saves your neighborhood’s trees.”
