Several state agencies united this month, asking the public to check nearby trees 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 are seeking information on wood-boring insects and the damage they cause in trees. Late summer is often the peak time for these invasive insects to emerge from trees in their adult stage.
The most alarming culprits to the agencies are long horned beetles, emerald ash borers and spotted lanternflies.
These species, so far, have not been spotted on Whidbey, said David Cass, a forester with Washington State Parks, but people still must check for them.
“Largely, the general public doesn’t think a lot about invasives until they’re already here,” he said. “That’s typical of all invasive species we are used to seeing and hearing about. The gypsy moth, for example, now called spongy moth, didn’t come to mind for people for the first decade or two that it was around in the U.S. until it was everywhere.”
A state study shows that over 70 insect species have been detected in Wahington since 1990, and 36% of these were first found by public reports.
The most dangerous offenders, Cass said, are likely right at Whidbey’s doorstep.
The emerald ash borer has been spotted in both Portland, Oregon and Vancouver, B.C., he said. There are only two ways this could happen.
“One is that it’s been dragged,” he said, “and the other is that it’s already in between and we just don’t know it.”
All three of these “wanted” species could happily live in Whidbey’s environment, he said. Longhorn beetles and spotted lantern flies attack a variety of hardwood tree species, which make up much of Whidbey. Ash borers prefer trees in the ash Fraxinus genus, which can be found in urban areas on Whidbey.
The damage caused by tree-boring pests varies by species.
“There’s other boring insects, you know, it gets quite boring, but there’s different mechanisms for attack for each of them,” Cass said.
Ash borers lay larvae into the stem of the tree, and the larvae feeds on the tissue underneath of the bark and the tree, preventing the sapwood from transporting water and nutrients, killing the tree over the course of a year or even a few years.
Spotted lanternflies, on the other hand, drip sticky, sweet “honeydew” over the tree, making it “really gross” and attracting other insects, Cass said, destroying the value of the tree. While these insects don’t outright kill the tree, they bring concern to recreators, loggers and park staff. Lanternflies have been intercepted in California hitchhiking on goods coming from eastern Washington, where they are established.
Long horned beetles are not known to be established anywhere in Washington, but they have been found and stopped several times in the past. These black, long-antenna beetles are sometimes mistaken for their native lookalikes, such as the banded alder borer and spotted pine sawyer, which are beneficial to Washington’s forests.
Indications of insect damage to trees include sudden dieback or death among an otherwise vigorous and healthy forest. Further investigation may present sawdust, exit holes or adult beetles themselves.
In addition to trees, these insects can show up in lights and standing water like dog bowls, bird baths and pool filters.
The best way to prevent invasive species is by not being vectors, Cass said. While it’s challenging to prevent them from moving into the state, people can sway how quickly they spread and how much damage they cause. One method of defense is introducing predatory wasps that eat ash borer larvae, he said.
Any sort of defense takes lots of time for research and field trials before it’s approved, he said, so slowing the spread is vital.
If a suspected invasive insect is found alive, the state encourages people to photograph and submit a report to the Washington Invasive Species Council at invasivespecies.wa.gov/report-a-sighting. If the species is found dead, collect and place the insect onto something with a white background, like a piece of paper, and photograph it from every angle. Then, place the insect into a sealable container. Entomologists may ask the reporter to mail the specimen in.
“Yours could be the report that saves your neighborhood’s trees,” said Stephanie Helms, Invasive Species Council executive coordinator, in a press release.
Other tips include keeping firewood where it will be burned, preventing moving insects that may be hiding in the pile, and checking bags, boxes and gear for insects before traveling.
“It only takes one,” Cass said. “One introduction to cause a massive amount of damage. Of course, state parks are known for their trees and forests, and that’s why we love and value them, so we want to do our best to protect them.”
Emerald ash borers lay larvae into the stem of the tree, and the larvae feeds on the tissue underneath of the bark and the tree, preventing the sapwood from transporting water and nutrients, killing the tree over the course of a year or even a few years. (Photo provided)
Spotted lanternflies have been intercepted in California hitchhiking on goods coming from eastern Washington, where they are established. (Photo provided)
