Cooler temperatures will be driving many insects indoors
Brown marmorated stink bug is a problem indoors & outdoors
The welcome mat outside the front door of your home is probably not intended for all species of life. Nonetheless, many insects jump at the chance- or more likely crawl- to find safe harbor and warm temperatures as winter approaches. Homeowners and apartment dwellers in Oregon may begin to notice the usual increased indoor activity of insects associated with this time of year, and the Oregon Department of Agriculture is hearing about it.
"We get calls throughout the year, but most of them come in fall and winter because several insect species- both introduced and native-enter homes in large numbers at this time," says ODA entomologist Jim LaBonte. "They may be a nuisance but homeowners should not be overly concerned with these bugs. They are not a threat to humans, pets, or structures in any way, manner, or form."
As temperatures drop and days become shorter, these insects can aggregate in houses and other structures. In nature, they seek winter shelter under loose bark, in rock crevices, rotten logs, and leaf litter. Unfortunately, human residences also work just fine as shelters. When such insects enter residences in large numbers, they can become what entomologists refer to as AHPs- aggregative house pests.
Because AHPs are relatively small- some species are very tiny- they can easily enter through gaps under and around doors leading outside, poorly fitting windows, dryer vents, and other points of access into a residence. While almost all species of AHPs feed on plants, they do not feed while overwintering and should not harm house plants. These insects do not reproduce while inside residences.
Keeping these bugs out in the first place is probably the best choice for residents.
"The best thing to do is to seal up points of access," says LaBonte. "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. ODA also receives 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.
In the past decade, a handful of exotic species have burst onto the local scene in high numbers.
One insect pest with an unsavory name and an unappealing scent first showed up in Portland in 2004, triggering a statewide alert asking citizens to help with detection. At the time, it was the first appearance of the brown marmorated stink bug, Halyomorpha halys, west of the Mississippi. Since then, several indoor detections have been made in the Portland area and the northern Willamette Valley, often in large numbers. The bug has been found as far south as Corvallis, east to Sandy, and west to Dallas, Forest Grove, and McMinnville.
The brown marmorated stink bug, first found in the US in 2001, is native to Japan, China, Taiwan, and Korea. While similar in looks to Oregon's native stink bugs, this one has no natural predators, parasites, or diseases in the US to help control its population. Where the bug has become established in Asia and back east, it can enter homes by the thousands, which can be stressful and disturbing to residents.
As creepy and crawly as the stink bugs may be, they won't cause harm to humans although, as the name suggests, they can release an unpleasant odor when disturbed. The major concern is for agriculture.
"Brown marmorated stink bug is now a major crop pest in the east, particularly the mid-Atlantic states," says LaBonte. "The insect feeds on more than 300 species of plants and commodities ranging from fruit to soybeans, and practically everything in between. It can reach high numbers and do a lot of damage just feeding on fruits and vegetables, rendering these commodities worthless in the marketplace. It can even damage trees by feeding on sap through the bark. No pesticides labeled for stink bugs are very effective against this species. There are no effective traps and lures commercially available for the insect pest, although research is promising."
Several other exotic species distantly related to the brown marmorated stink bug have also been reported as being AHPs in Oregon. 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. Several years ago, the multi-colored Asian ladybird beetle, Harmonia axyridis, imported to control Russian wheat aphid, was a frequent source of calls to ODA. That has not been the case recently.
Homeowners will also notice 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, according to LaBonte.
So far, this appears to be a normal year of indoor bug activity in Oregon. LaBonte would not be surprised to see an increase in brown marmorated stink bug detections, especially in the Portland area. No matter the species, its normal for you to share your home this winter with insects whether you like it or not.
For more information, contact Jim LaBonte at (503) 986-4749 or Barry Bai at (503) 986-4645.
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