The interlopers arrived in mid-July.
They would cluster around outside walls, bask on windowsills and wander into bedrooms and bathrooms. They posed no harm, but smelled a little funky.
Paul Krupin didn’t recognize the uninvited guests at first glance — they had never before visited his south Kennewick home. He and his wife, Nancy, leafed through books trying to identify the visitors. They formed theories and consulted experts. The interlopers were positively identified in October.
They were elm seed bugs, and they had never before been found in Washington.
Specimens provided by Krupin, 62, to a local Washington State University Extension office proved to be the first evidence of the nuisance bug’s presence in the state and just the second report in the nation. The bugs were first found in 2012 in the Treasure Valley region of western Idaho and eastern Oregon. They are native to south-central Europe and likely entered the U.S. accidentally.
“We suspect that they may have tried to overwinter in cargo,” said Mike Bush, an entomologist with WSU’s Yakima extension office.
Bush said elm seed bugs have likely established themselves in Krupin’s south Kennewick neighborhood, meaning they won’t be leaving. During the hot summer months, Krupin said thousands would congregate around his home and penetrate the building through the smallest of openings.
“As exciting as this find is to entomologists, it is not good news for those of you most (likely to) deal with hordes of invasive seed bugs congregating on homes,” Bush told Krupin.
The Krupins, who have biology degrees from Oregon State University, initially thought the insects could be elder bugs, but they knew elder bugs were larger than the insects clinging to the windows and burrowing in the eaves. They searched insect books trying to find a match. Eventually they found the elm seed bug and thought they had a positive ID. The Krupins presented their theory to the WSU extension office in Kennewick.
“They agreed with our tentative diagnosis,” Krupin said.
The Kennewick WSU extension office sent samples to other extension services in Yakima and Olympia. Eventually they made their way to a specialist at the Smithsonian Institution that confirmed the insects were elm seed bugs.
The state Department of Agriculture photographed and cataloged Krupin’s specimens, and a number of the bugs were deposited in the WSU Insect Collection in Pullman. Krupin appreciates his contribution to science, but the elm seed bugs have proved tiresome.
“Everywhere there was a crevice you’d find dozens of them,” Krupin said.
The bugs don’t bite or destroy vegetation, but they do emit an unpleasant smell when crushed. Krupin described it as a “formic acid odor.”
He thinks the bugs were attracted to his South Lyle Street neighborhood by a stand of nearby elm trees. Elm seed bugs borrow their name from their primary food source — the seeds of elm trees, although they’ve been known to feed on oak and linden trees in Europe.
They hibernate during the winter and emerge in the spring to mate and lay eggs. During the hot summer months they enter homes and buildings to escape the heat. During autumn they may come inside in preparation for winter hibernation.
“They seem to be diminishing, but there were a couple in here (Tuesday) night,” Krupin said last week.
He has spent hundreds of dollars on bug-killing chemicals. “We’ve tried everything that’s available,” Krupin said.
He and his wife eventually resorted to a vacuum cleaner to remove the pests from walls and windows. Krupin brought in a hired gun too.
“We’re kind of at a point right now where it’s cold and most of (the bugs) are in a hibernation format,” said Paul Nyman, owner and operator of Nyman Pest Control in Kennewick. He added, “We’re not sure what product is going to eradicate these bugs.”
Nyman is going to reach out to pest control experts in western Idaho to see how they’ve addressed their elm seed bug infestation.
“The Nampa area seems to be infested with these things,” Nyman said. “I’m going to call some people because what I want to do is contact some people that have dealt with these things.”
Nyman has spent more than 20 years in the pest control industry. He called the challenge of treating a previously unknown pest is kind of fun.
“You feel like the mad scientist,” he said.
Krupin hopes to seal his home this winter and attack the elm seed bugs when they emerge from their hibernation during spring. At that point, he’s hoping the bugs lead an exterminator to their source. The infestation is not limited to one home. Krupin said he’s walked up and down his block talking to neighbors. Many have had the same problem.
“We may be stuck with this for the rest of our lives,” Krupin said. “We may be able to slow (the bugs) from house to house.”
Bush encouraged people to alert their local WSU extension office or a master gardeners group if they spot elm seed bugs in their neighborhood.
“I suspect it will continue to spread,” Bush said.
If you use a vacuum cleaner to remove the pests from your homes, Bush recommends you leave the vacuum cleaner outside because of the bugs’ odor and ability to escape.