Summary: Fall is peak season for pest invasions across the Midwest. Learn which fall pests (mice, spiders, stink bugs, and more) hit St. Louis homes the hardest, plus prevention steps that actually work against these fall pests.

______________________________________________________________________________________________________________________________________

As the weather gets cooler, insects, spiders, and rodents are more desperate to invade our homes than ever. They need a warm shelter to survive the winter and emerge in the spring to start growing their numbers again.

We see so many fall pests because they exploit the forgettable gaps on houses and buildings. Cracks around utility lines, spaces under doors, and unscreened attic vents become easy entry points. The result? More fall pests that want to make themselves comfortable just as you’re settling in for the coziest seasons.

Let’s take a brief look at the 8 most common fall pests before we give our top tips on keeping your home pest-free all year long.

The Usual Fall Invaders in St. Louis

Every region has its own set of common pests since the weather, resources, and topography vary with location. That’s why it’s important to familiarize yourself with the fall pests most common to your region. When you know your pests, it’s much easier to prevent them!

These are the 8 pests you’re most likely to see this fall in the greater St. Louis area:

House mice – Small openings the width of a pencil are all they need to get inside. The good news (sort of) with mice is that they leave a lot of evidence behind. Droppings, gnaw marks, shred nesting material, chewed packages, scratching or squeaking sounds, live mice, and smudges on the walls are all signs of a rodent issue.

Rats – Norway rats usually invade homes on the ground level and create burrows near house foundations. They contaminate everything they touch and often chew through electrical wiring, which is a major fire hazard. The signs of a rat problem are basically the same as a mouse problem, except for one thing: rats are less outgoing than mice!

Spiders – Wolf spiders and brown recluses become more noticeable in the fall, especially since they don’t live in sticky webs like a lot of other spiders. As they follow their prey and hunt for dry, undisturbed spots, spiders find themselves in our homes for the season. If you’re seeing more webs or spiders indoors, there could be a larger pest problem at hand.

Boxelder bugs – These red-lined bugs congregate on the sunniest parts of houses, buildings, and boxelder trees (naturally) in the fall. Then, they try to find a gap in the nearby structures to secure their overwintering shelter. They’re harmless, but having an army of boxelder bugs in your home is not a fun fall activity.

Brown marmorated stink bugs – Similar to boxelder bugs, brown marmorated stink bugs gather in sunny areas before trying to invade their desired winter shelter. Their signature odor only comes out when they are squished or threatened. But when there’s a huge group of them indoors, the smell becomes more apparent.

Asian lady beetles – Often mistaken for ladybugs, they cluster in the hundreds on light-colored, sun-facing walls. These beetles also want to get inside our homes before winter sets in, but they’re just another nuisance we don’t want in our space. Asian lady beetles release a smelly spray that stains surfaces when they’re threatened, so look out.

Cluster flies – These weirdly fuzzy flies prefer to overwinter in wall voids that get warmed by the sun. That’s why they’re often found in attics, garages, and bathrooms. When a fall or winter day is especially warm, it’s not uncommon to see cluster flies gathering (or clustering, if you will) on or near windows.

Centipedes – These nocturnal pests prefer to stay in damp environments with dark spaces for them to hide in between searching for prey. Basements, bathrooms, and garages are their usual habitats. Centipedes look like alien critters that have too many legs for our liking, so it’s a small consolation that they don’t want anything to do with us.

What Actually Keeps Fall Pests Out

Instead of scouring the store shelves for a spray that might solve your pest problems, try our recommended DIY tips for a pest-free home! These are tailored to fit the fall season, but they’re good to keep in mind year-round. Keep in mind that these tasks are most effective when paired with professional services.

The tasks we recommend for keeping fall pests out of your home are:

Seal cracks and gaps (especially near utility penetrations) with exterior-grade caulk. If the openings are larger, fill them with steel wool before lining with caulk.

Install door sweeps on exterior doors to eliminate unnecessary gaps. Replace loose weatherstripping on doors and windows that aren’t tightly sealed.

Make sure the garage door’s seal is flush with the ground. If the seal is loose or the door is warped, contact your local garage door repair service.

Repair broken screens on foundation, soffit, and attic vents. Add tight-fitting screens to chimneys and utility openings that don’t have one yet.

Reduce extra moisture by clearing out the gutters, extending downspouts away from the house, fixing leaks, and running a dehumidifier in rooms that retain humidity.

Store pantry essentials (cereal, chips, baking ingredients, etc.) in airtight containers. If you have a dog or a cat, store their dry food and bowl in a lidded container after each meal.

Keep a clean kitchen by wiping down the counters, sweeping under the fridge and range, and taking out the trash when it’s full. Don’t let dirty dishes sit in the sink for more than a day.

Store your firewood pile at least 20 feet from the house and off the ground. Keep it covered to prevent the wood from getting wet and rotten.

Tidy up the yard by raking leaves and trimming shrubs and tree branches at least 1 foot away from the house. Ensure the lawn and soil drain properly after it rains or the sprinklers run.

Replace bright exterior bulbs with warm-temperature LEDs near doors to attract fewer insects and spiders. Turn off unnecessary lights at night to lower the attraction for nocturnal pests.

When DIY Isn’t Enough

Seeing spider webs in corners or mouse droppings in the garage? Pointe Pest Control is here to help! Our targeted treatments and thorough inspections are designed to keep even the worst fall pests out of local homes and businesses.

Our state‑certified technicians use Integrated Pest Management to solve problems quickly and safely, with solutions tailored to your property. If a pest issue isn’t fully resolved after a visit, we will return at no extra cost.

For focused help, check out our Spider Control in St. Louis and Rodent Control in St. Louis.

Prefer to talk it through? Request a quote from our dedicated team today!

Citations

Occasional invaders. (n.d.). Illinois Department of Public Health. Retrieved September 29, 2025, from https://dph.illinois.gov/topics-services/environmental-health-protection/structural-pest-control/occasional-invaders.html

Why fall pest prevention matters now. (2025, September 1). Bug Zero. Retrieved September 29, 2025, from https://bugzero.com/why-fall-pest-prevention-matters-now/