Insects Invading Your Home?

They appear suddenly, seemingly out of nowhere, massing (sometimes by the thousands) on the west wall and windows of your kitchen, or perhaps as swarms of lazy flies buzzing annoyingly and aimlessly around the room.

If you live in a part of the nation where temperatures can dip below freezing from late fall into early spring, the cold-weather insect invasion can be a real nuisance.

These are the five main culprits, with links to learn more about them:

• Multicolored Asian lady beetle
• Cluster flies
• Western conifer seed bug
• Boxelder bug      
• Brown marmorated stinkbug

Left: Western conifer seed bug. Right: Cluster fly.  Credit: Alan T. Eaton, UNH.edu

Depending on the structure and exterior finish of your home, as well as environmental factors such as the surrounding vegetation around and near it, some years you may see a lot of these critters, other years, few or none.

The Good News

None of these cold-weather invaders will eat your food, bite, sting, spread diseases to people or pets, infest stored foods, eat fabrics or paper, destroy wood, or cause any kind of structural damage. (Note: The one exception is the Asian lady beetle, which is capable of biting.) What’s more, they won’t mate, lay eggs, and reproduce within your walls or inside your home. They live off their stored bodyfat until spring.

However, when swatted or squashed, stinkbugs, as the name suggests, emit a foul odor emitted by the scent glands when the insect is disturbed. When stressed or dying, a mass of Asian lady beetles may also smell bad and release a yellow fluid that can stain fabrics. Also, the feces of any large mass of insects may help trigger allergies in some people.

How do they get in?

These insects crawl in through loose siding, cracks, crevices, vents, holes in screens, etc. They may fly in through open doors and windows.

What can you do about them?

Prevention, as always, is the best way to deal with these unwelcome visitors. You know the drill: Seal cracks in doors, windows, and openings where air conditioners, plumbing, phone and TV wires enter the home with weather stripping, caulking, polyurethane foam or other appropriate materials.

Make sure your doors and windows shut tightly and keep them closed. Also window screens need to be in proper shape without any holes; keep screens shut tightly, too.

Once the insects have come inside, you can brush the crawlers into a bowl of soapy water (add a bit of detergent). This method gets rid of their odor, too.  You can also sweep/vacuum* the bugs up. If you vacuum, empty the bag or canister immediately to prevent the insects from escaping or they will simply reappear back inside the home. Swat the flies.

Please don’t spray insecticides! Most insecticides have some degree of toxicity to people, and spritzing these products around inside a home or car will increase exposure to humans and pets. Besides, you aren't likely to kill the ones hibernating inside your walls. If you did kill some of them the scent of the dead ones might attract other insects to scavenge their remains.

The insects that do survive in your walls or attic will leave with the return of warm spring days, and it’s not likely you’ll see them in or around your home again until fall.
 

*Because I have a little solar greenhouse attached to my kitchen, I welcome lady beetles seeking shelter in my home. I just sweep or scoop them up and relocate them into the greenhouse to feast on the aphids that invariably show up to feast on my cooking and salad greens.

Some gardeners overwinter ladybeetle invaders in glass jars in the refrigerator and release them outdoors in spring. If you try this, spritz occasionally and lightly with water, or place a small piece of moist (not wet) paper inside the jar to prevent the insects from drying out.

See the Almanac's pests and problem page for more insect information.