17/10/2025
As the temperatures drop here in Illinois, pests aren’t dying off — they’re moving in.
This time of year, bugs and rodents start searching for warmth, shelter, and food. Unfortunately, your cozy home checks every box.
Here are some of the biggest culprits that show up each fall and what’s really going on behind the scenes 👇
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🕷️ 1. Spiders on the Move
If you’re suddenly noticing more spiders around your home, you’re not imagining it.
Fall is their mating season, and male spiders are wandering indoors in search of females. They often sneak in through tiny cracks around doors, windows, and foundation gaps.
While most spiders are harmless, a few (like the brown recluse) can pose risks — so if you’re finding more than a couple, it’s worth scheduling a professional inspection.
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🪲 2. Stink Bugs & Boxelder Bugs
These flat, shield-shaped bugs show up in big numbers around late September and October. They gather on sunny sides of houses and slip inside through vents, siding gaps, and window screens as temperatures drop.
Stink bugs won’t bite, but they release a strong odor when crushed or disturbed. Once inside, they can overwinter in attics, wall voids, and light fixtures — meaning you might still see them on warm winter days.
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🐜 3. Ants Relocating Indoors
Ants don’t hibernate — they simply move to warmer areas when it gets cold. That often means under floors, behind walls, or near heating vents.
Carpenter ants, in particular, can be destructive since they burrow through damp wood, weakening structures over time.
To prevent this, seal baseboards, fix leaky pipes, and keep food tightly stored — even crumbs are enough to attract a colony.
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🐭 4. Rodents Seeking Shelter
As soon as nights dip below 50°F, mice and rats begin scouting for warmth.
A mouse can squeeze through a hole the size of a dime, and once they’re in, they’ll multiply quickly.
Signs of activity include droppings, scratching noises in walls, or chewed food packaging.
Rodents can spread bacteria, trigger allergies, and chew through electrical wires, which is why exclusion and prevention are key before winter hits.
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🐝 5. Wasps & Yellowjackets
By fall, wasp colonies are dying out — except for the queen, who’s searching for a place to overwinter.
You’ll often see more aggressive wasp behavior this time of year because their food sources (like nectar and fruit) are disappearing.
They’re attracted to outdoor garbage, soda cans, and fallen fruit — so keeping those areas clean makes a big difference.
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🦟 6. Mosquitoes & Ticks
Even though you’d think mosquitoes vanish when summer ends, they hang around until the first hard frost.
They thrive in standing water trapped in gutters, toys, or leaf piles.
Ticks also remain active on mild fall days and can hitch a ride inside on pets or clothing.
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🐞 7. Lady Beetles (a.k.a. “Asian Ladybugs”)
These look just like cute ladybugs, but they’re actually an invasive species that bites and stains surfaces.
They cluster around windows and attics as the weather cools, releasing a strong odor when squished.
They enter through vents and small cracks around window frames — professional exclusion is the best solution to keep them out for good.
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🔍 8. Prevention Is Everything
Most fall pest problems come down to one thing — easy access.
Here’s what you can do right now to protect your home:
• Seal gaps around doors, windows, and siding
• Replace worn weatherstripping
• Store food (and pet food) in airtight containers
• Keep firewood at least 20 feet from your home
• Clean gutters and clear out leaf piles near the foundation
If pests have already found a way inside, Pestmaster Naperville/Wheaton can help with targeted treatment and prevention that’s safe for your family and pets.
