Washington Invasive Species Council

10/22/2026

As you take in the beautiful fall colors across Washington, keep an eye out for these invasive noxious weeds that also transform, trading their bright flowers and green leaves for a new fall look.

These species damage Washington’s ecosystems by outcompeting native plants and reducing habitat for native wildlife, sometimes even changing soil conditions and increasing the risk of wildfires.

Knowing what these invasive plants look like year-round is important, so you don’t accidentally spread them. Plants like scotch broom shouldn’t be removed in the fall because it can cause more seeds to spread and germinate. It should be pulled in early spring. Learn more about what plants to watch out for at https://invasivespecies.wa.gov/find-a-priority-species/?_sft_priority-specie-type=noxious-weeds

Photos courtesy of Tim Harrington, Richard Old, Tom Heutte, USDA Forest Service, Steve Dewey, Utah State Univ., Bugwood.org

10/21/2026

It might look like these are both Asian longhorned beetles . . . but look again!

One is the invasive insect that can eat more than 40 species of healthy Washington trees. The other is just a furry friend in a spooky costume.

Luckily, this invasive beetle has not yet been established in Washington, but it has been found and intercepted in plant material entering the U.S. through Washington. Asian longhorned beetles can look very similar to native species like the banded alder borer and the white spotted sawyer. While these native species will only feed on dead or dying tree branches, Asian longhorned beetles can harm healthy trees.

Learn more about how to distinguish this invasive species from its native look-a-likes at https://invasivespecies.wa.gov/priorityspecies/citrus-asian-and-red-necked-longhorned-beetles/

10/20/2026

Looking for the villain that can cover boats, clog pipes, and shut down access to state waters? Mystery solved — it’s the zebra mussel!

Zebra mussels are an invasive freshwater species that have already become widespread in the Great Lakes and across the eastern U.S. Experts estimate the total cost of infrastructure damage (like power plants and hydropower facilities), water treatment, and fisheries impact from clogged intake pipes and filters to be over $1 billion each year.

They are not yet in Washington, but quagga mussels, a closely related species, have been detected in the Snake River in Idaho. You can help stop the spread by making sure to fully clean, drain, and dry all boats and aquatic gear when leaving and before entering a new body of water.

Learn more at https://invasivespecies.wa.gov/priorityspecies/zebra-and-quagga-mussels/

10/15/2026

Washington State Department of Agriculture confirmed a second report of emerald ash borers in Washington. An infested ash tree was found in Walla Walla County and reported by an arborist who identified many signs of an infestation, including D-shaped exit holes, canopy dieback, and woodpecker activity.

Check your ash trees for these signs and share this information to help with early detection of this destructive pest.

Learn more at https://invasivespecies.wa.gov/priorityspecies/emerald-ash-borer/

Photos courtesy of Oregon Department of Forestry, Pennsylvania Department of Forestry, Gosztyla, WA DNR UCF, Art Wagner, USDA, Bill Hebner, and Daniel Herms, Bugwood.org

10/15/2026

WSDA press release: https://agr.wa.gov/about-wsda/news-and-media-relations/news-releases?article=47423

Learn how to identify an emerald ash borer and monitor ash trees for signs of an infestation: https://invasivespecies.wa.gov/priorityspecies/emerald-ash-borer/

🚨 Do you live in County? An alert arborist spotted suspect emerald ash borer larvae in a tree in the College Place area. We responded to the report, and both we and USDA confirmed the specimens as . Learn more in our latest press release.

10/14/2026

Do you have what it takes to be an invasive species detective? Look carefully!
One of these pictures is an invasive red swamp crayfish, which is widespread through the Sammamish River basin, and outcompetes native crayfish for food and habitats, also impacting native fish populations. The other . . . is a chicken.

Red swamp crayfish were introduced to the area by human activity, likely as a released aquarium pet or as fishing bait. Learn more about the three species of invasive crayfish in the Pacific Northwest at https://invasivespecies.wa.gov/priorityspecies/non-native-crayfish/

Photo courtesy of USGS, Bugwood.org

10/13/2026

Are you ever out in the woods, and get the feeling that you’re not alone? Or something is watching you?

Invasive species like spongy moth larvae are waiting for their chance to hitch a ride with you to infest a new forest. You can help stop the spread of invasive species by making sure to fully clean your gear and vehicles and remove all plant material and anything that could hide invasive insects.

Learn more about the different pathways invasive species can spread at https://invasivespecies.wa.gov/address-pathways/

Photo courtesy of Washington State Department of Agriculture, idea from Don't Move Firewood

10/08/2026

October is Firewood Month! Be sure to check local rules and burn restrictions before lighting a campfire, and don’t bring along any unexpected guests on your next trip!

Invasive species like emerald ash borers, spongy moths, and invasive longhorned beetles can hide under the bark of firewood, and with your help they can hitch a ride to a new forest and establish an infestation.

Help protect the places you love this fall by practicing campfire safety and keeping firewood local! As a general rule, don’t move firewood more than 10 miles, and buy or gather (where permitted) firewood when you arrive at your destination. Only heat-treated wood certified as pest-free can be brought into the state. Learn more about how to protect Washington’s forests at https://invasivespecies.wa.gov/campaigns/buy-it-where-you-burn-it/

Photos courtesy of Art Wagner, USDA-APHIS, and Pennsylvania Department of Conservation and Natural Resources, Bugwood.org

10/07/2026

The Washington Invasive Species Council is excited to announce the fourth annual Halloween Invasive Species Pet Costume Contest! Demonstrate your creativity, learn about invasive species, AND show off your pet in costume!

This contest intends to raise awareness of the “Don’t Let It Loose” campaign, which seeks to prevent the release of pets into the wild. Unwanted pets or exotic animals can become invasive species and harm Washington’s natural resources. Email submissions to [email protected] by October 28 to enter. For more information and contest rules: https://forms.cloud.microsoft/g/zEqX1dujP6

10/06/2026

It’s another great day to report invasive species sightings! Pretty fetch, right?

We rely on citizen scientists like you to be our statewide network of invasive species detectors. Help spread the hot gossip on invasive species sightings and keep the “Mean Bugs” out of Washington.

Your reports help us track the spread of invasive species and detect new infestations early, so we can respond quickly and prevent further spread.

Learn more about what we do with your reports: https://invasivespecies.wa.gov/report-a-sighting/