The Main Entry Points Fall Insects Use to Invade Homes

When temperatures drop in the fall, insects look for warm, sheltered places to survive the coming winter. The most common entry points they use to get inside houses are gaps, cracks, and small openings—often ones homeowners may never notice. Specifically, insects such as stink bugs, boxelder bugs, ladybugs, spiders, and ants tend to exploit the following spots to invade:

• Gaps Around Windows and Doors: Even tiny spaces between the frame and the wall or old weather stripping provide a perfect entrance for insects. If sunlight or outdoor air slips through, insects can too.
• Cracks in Foundations and Walls: Shrinking and settling of a house over time creates cracks in exterior walls and the foundation. Insects easily find and enter through these small routes, especially near the ground.
• Gaps Around Utility Lines and Pipes: Where utility lines, pipes, or air conditioning systems enter your home, there are usually small gaps or holes not fully sealed that make ideal entry points.
• Vents and Attic Openings: Dryer vents, attic vents, or bathroom exhaust fans often have covers that aren't insect-proof, especially if screens are torn or missing.
• Chimneys and Rooflines: Open chimneys and gaps at the edge of the roof or under loose shingles are hidden ways for insects to come in, particularly if the chimney lacks a tight cap or mesh.
• Damaged or Missing Window Screens: Screens with rips or holes are an open door for flying insects. Sometimes, screens aren’t fitted properly, leaving a gap along the edge.
• Basement Windows and Window Wells: These areas are close to the ground, so they collect moisture and warmth, attracting insects to slips in the seal around the frame or glass.

How Fall Insects Find and Use These Entry Points

Insects are very sensitive to temperature and air flow. As it cools outside, they are drawn toward:

• Warm air and heat leaking out of buildings. Even the tiniest stream of warm air escaping through a gap will attract insects in search of shelter.
• Dark, moist, or sheltered spots. Corners, cracks, and crevices resemble the natural spaces insects hide in outdoors.
• Scent trails. Some insects can detect leftover food, plants, or the presence of other insects, leading them right to potential openings.

Because most fall invaders are small and flexible, they only need the tiniest space. For example, a stink bug or ant can squeeze through a gap thinner than a credit card. Many bugs are skilled at climbing walls to access even upper stories or roofline cracks.

What You Can Do to Block These Common Entry Points

To prevent insect invasions in the fall, it’s important to “bug-proof” your home by sealing up these key access points. Effective steps include:

• Install or replace weather stripping along windows and doors to eliminate gaps.
• Seal foundation and wall cracks using high-quality caulk or expanding foam.
• Install mesh or screens (with fine holes) on attic vents and over chimneys, and repair any holes in window screens.
• Inspect and seal around pipes, cables, and utility lines with appropriate sealant or weather-resistant materials.
• Keep basement windows tight and window wells covered with secure screens or covers.
• Check for gaps along roof edges and under siding, especially where different building materials meet.

Doing a careful walk-around outside your home, especially before temperatures drop, helps you spot where seals have worn down or shifted. Preventing entry is much easier and healthier than dealing with an infestation later, and focusing on these common access points will save you time and trouble every autumn.