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Stink bugs look for a home in Oregon, maybe yours
Many insects head indoors for the winter, including the brown marmorated stink bug

It’s the annual rite of late autumn. Insects jump at the chance, or more likely crawl, to find safe harbor in homes as the temperatures drop. For Oregonians, the list of unwanted house guests now includes the brown marmorated stink bug, an invasive pest that is mainly a nuisance for residents but a huge economic threat to agriculture.

The Oregon Department of Agriculture is beginning to get more calls from homeowners noticing the stink bug. That’s to be expected since the population of the crop-eating bug is increasing and spreading fairly quickly throughout the state.

“We believe the initial infestation was in southeast Portland, but at this point, we have 10 counties we know are infested with brown marmorated stink bug and another six where it has been reported to be found,” says ODA entomologist Josh Vlach. “It hasn’t even been a decade since it was first found in Oregon. We’ve seen it as far east as Umatilla County and as far south as Jackson County.”

It appears the exotic stink bug is here to stay in Oregon. The pest has been found in such agricultural production areas as the Willamette Valley and Hood River. On a pest risk scale of 1 to 10, it has been described by some to be a 15. Native to Asia, the brown marmorated stink bug has no natural predators, parasites, or diseases in the US to help control its population. ODA is the lead regional agency for conducting research on finding a biological control agent to work against the bug, but results may be a few years away.

While the insect has caught the attention of officials because of its potential to damage a wide array of agricultural crops, it is the homeowner this fall and winter who might see more immediate evidence of the brown marmorated stink bug– especially anyone who might have attracted the pests earlier in the year by having a backyard garden.

“Oregonians might find several hundred coming into their homes, but back east, where the stink bug has become well established in high populations, some homeowners are seeing up to 50,000 of these bugs inside their house,” says Vlach.

As creepy and crawly as the stink bugs may be, they won’t cause harm to humans although, as the name implies, they can release an unpleasant odor when disturbed.

“They are not harmful outside the agricultural setting,” says Vlach. “They don’t bite. Since they do not feed while overwintering, they will leave your house plants alone. They won’t bother your pets. They might hide underneath your picture frames or get snuggly in your couch, but they really won’t hurt anything inside the house. Unfortunately, they do stink when agitated.”

The best advice for brown marmorated stink bug is the same advice for any insect potentially becoming your housemate– keep them out in the first place. Some species are much smaller than the stink bug and can easily enter through gaps under and around doors leading outside. They can also wiggle their way through poorly fitting windows, dryer vents, and other points of access into a residence.

“Seal up points of access,” says Jim LaBonte, another member of ODA’s team of entomologists. “For bugs that have already entered the home, it depends on how many you have and your tolerance to these insects. You can escort them outside, flush them down the toilet, or dispose of them as you see fit. If there is a large number of them, a vacuum cleaner works well. We don’t recommend calling a pest control company this time of year. First, these bugs aren’t harmful. You should be able to deal with them on your own. Secondly, your home is like an island in a sea of bugs. Spraying pesticides, might get rid of pests inside the house at that time, but others likely will come in and take their place, especially if you haven’t sealed the accesses.”

After a few hard frosts, the outdoor bugs will likely become very inactive or will have already found shelter for the winter. In either case, they aren’t likely to come indoors.

Several native species find their way into the home during winter, most commonly the box elder bug, which normally feeds on maple leaves. In the past, ODA has also received numerous calls and contacts about the native western conifer seed bug, Leptoglossus occidentalis, a leaf-footed bug sometimes mistaken for the "conenose" or "kissing" bug. That bug is a species of assassin bug, which bites people, sucks their blood, and can transmit Chaga's disease. However, "conenose/kissing" bugs are not found in Oregon.

Other exotic species distantly related to the brown marmorated stink bug have also been reported  in Oregon as insects that will aggregate in homes. These include the big-nosed bug, Metapoplax ditomoides, and the tuxedo bug, Raglius alboacuminatus, as well as two species without common names, Rhyparochromis vulgaris and Xanthochilus saturnius. None of these are known to be crop pests.

A new insect pest this year to be reported in eastern Oregon is the elm seed bug, discovered across the Snake River in western Idaho this past summer when the hot weather drove them indoors in many homes.

Homeowners may also see a variety of spiders indoors this time of year. Harmless web-producing garden spiders, and various house or ground spiders are more noticeable in the winter months as they enjoy the warm confines of someone’s residence. These spiders are nothing to be concerned about.

As recently as last year, ODA was very interested in hearing from homeowners who might have discovered brown marmorated stink bug living under the same roof. However, the increasing population of the pest has made it well established, especially in the Willamette Valley. The only regions of the state yet to detect the stink bug are the Oregon coast and southeastern Oregon.

Whether this ends up being a bad year for indoor bug activity remains to be seen. Like it or not, it isn’t unusual to have to share your home over the winter with insects, including the brown marmorated stink bug.

For more information, contact Josh Vlach at (503) 986-6458.

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