Stink Bugs & Boxelder Bugs: Fall Infestations in the PNW

Cooler weather sends stink bugs and boxelder bugs exploring for shelter

Being a certified entomologist is not necessary to know that the cooler seasons give insects a clear-cut agenda. Like many insects, stink bugs and boxelder bugs seek shelter when the season changes from summer to fall. Typically during spring and summer months, stink bugs and boxelder bugs spend their time outdoors, often high in treetops, away from normal human activity. It’s the drop in temperatures that the fall season brings that start these insects looking for warmth and shelter to ride the winter out.

To prevent a boxelder bug infestation, it is crucial to install door sweeps on all exterior entrances to seal potential entry points during the fall season.

What a traveling little stink bug can cause

Without knowing it, insects hitch rides aboard cargo ships and travel to the United States from overseas. Stink bugs arrived from Asia in the 80s and landed in U. S. cornfields. These insects have caused the vast destruction of local crops upon their arrival. Today there are more than a thousand various species of stink bugs in the world. The most common of these bugs here in the U. S. is the Halyomorpha halys (brown marmorated stink bugs), and the Acrosternum hilare (green stink bugs). Their backs look like shields and easily blend into their environment. These bugs release an odor that does stink if they feel threatened by an adversary. Despite the fact that these bugs require diligent pest control, they are not harmful to humans or their homes.

The diet of a stink bug

The majority of stink bugs feed on plants. The young stink bugs feed on weeds and grasses, as they grow into adulthood they migrate into residential landscapes, orchards, or field crops. These bugs love feasting on beans, pecans, corn, peppers, apples, berries, cotton, corn, sorghum, and ornamental plants. When this bug gorges on his fruit, he leaves his saliva behind, which marks the fruit, leaving it scarred and unfit for sale. This insect is known to also spread disease. Here in the Portland and Vancouver areas homeowners rarely see stink bugs in the summer months as they feed high in tree foliage.

Another stinky bug, the boxelder

Boxelder bugs are another type of bug that uses their stink to protect themselves. They are not harmful to humans but more of an annoyance. Boxelder bugs have deep brown outer wings with red markings. These bugs feed on seedpods of seed-bearing boxelder trees as well as their flowers and leaves. Besides the boxelder tree, boxelder bugs also feed on ash trees and maple or ash trees. These insects can also be found on various trees and shrubs in residential landscapes, where they may cause damage to ornamental plants. They also have been known to eat plants bearing plums, grapes, pears, peaches, cherries, apples, and almonds. The fruit of these trees ends up deformed from the boxelder bugs’ perforations.

What Are Boxelder Bugs?

Boxelder bugs are small, black insects with distinctive red or orange markings on their wings and bodies. Named after the boxelder tree, their primary host, these bugs are more of a nuisance than a threat. While they don’t cause significant damage to plants or structures, their tendency to congregate in large numbers on buildings, especially in the fall, can be quite bothersome for homeowners. Despite their alarming appearance, boxelder bugs are harmless to humans.

Boxelder Bug Life Cycle and Behavior

Boxelder bugs undergo a complete metamorphosis, progressing through three stages: egg, nymph, and adult. In the spring, female boxelder bugs lay eggs on the trunks, branches, and leaves of host trees. These eggs hatch into nymphs, which feed on the sap of the host tree and molt several times as they grow. As they mature into adults, boxelder bugs feed on the seeds and leaves of the host tree. During the warmer months, these bugs are most active and often gather in large numbers on warm surfaces like rocks, trees, and buildings.

Look for shelter in the fall

Come September and October, as the cooler weather draws near, diligent pest control is advised to control these bugs. Adult stink and boxelder bugs will search for dry spaces in the crevices and cracks in walls, in the moldings around windows, cracks in house foundations. As the weather turns colder, these bugs will seek out any crack and crevice to gain access to the warmth of the interior of your home. To prevent these bugs from entering your home, it is essential to seal cracks and crevices using high-quality silicone or silicon-latex caulk.

Stink and boxelder bugs also seek shelter in hollow tree trunks, under rocks, and under woodpiles to live out the winter. If these bugs are evident in your home in the fall, come spring you’ll start seeing them again as they emerge from winter hiding to once again explore the outdoors. If boxelder bugs are found inside your home, physical removal is the most effective method, as insecticides are not practical or recommended.

Overwintering and Hibernation

As fall approaches and temperatures drop, boxelder bugs begin their search for protected areas to overwinter. They often enter homes through cracks and crevices in the foundation or walls, or find shelter under tree bark and in leaf litter. During the winter, boxelder bugs enter a state of dormancy called diapause, where their metabolism slows, allowing them to survive on stored energy reserves. When spring arrives and temperatures rise, boxelder bugs emerge from their winter hiding spots to feed and mate, starting their life cycle anew.

Avoid a boxelder bug infestation by winterizing the yard and home

Inspecting gardens and homes determines what steps are necessary to prevent a massive infestation of stink or boxelder bugs. Cleaning out all the debris around the foundation of the house, corners of fences, decorative rocks, old piles of wood, and patio furniture helps to eliminate hiding places for bugs seeking refuge from the cold. On windows and doors replace torn screens as well as caulk around the molding of the windows, vents, cracks in stucco and bricks restricting additional hiding places and protection for bugs from the winter chill. Removing boxelder trees from your property can significantly reduce the presence of these bugs. Maintaining a clean yard by removing plant debris can also help in controlling boxelder bug populations.

Sometimes no matter what you do as a homeowner, stink and boxelder bugs will be a problem. Sealing up cracks around roof soffits, windows, siding, and foundations can go a long way in preventing these insects from invading the interior of your home. Another helpful and most times successful tactic is to enlist the help and expertise of an experienced pest control company. Pest control companies with experienced technicians can offer expert advice on controlling these bugs through an effective treatment plan to keep your home protected. For additional control, consider using insecticides labeled specifically for boxelder bugs, but be sure to follow product instructions and be aware of potential side effects. Call us today to get an experienced PURCOR technician to your Northwest home or business ASAP!