October — Overwintering Insect Window
- Seal all exterior gaps before aggregating insects find them — Caulk gaps around window frames, door frames, utility penetrations, and the foundation perimeter. This is the last practical window before stink bug and boxelder bug aggregation peaks. See: Stink Bug Control, Boxelder Bugs
- Replace or repair door sweeps on all exterior doors including garage — Door sweep condition degrades over summer use. Replace any that no longer contact the threshold fully — this is a primary overwintering insect and rodent entry point.
- Apply exterior perimeter treatment to foundation and south-facing walls — A residual insecticide applied to foundation surfaces and the first few feet of siding in early October knocks down aggregating insects at entry points before they push inside.
- Check and seal attic vent screens — Stink bugs and cluster flies entering through attic vents produce the most persistent overwintering populations. Replace any damaged vent screens with fine mesh (less than 1/16 inch) before the aggregation peak.
- Set snap traps in garage along perimeter walls — Mouse migration into heated structures begins when outdoor temperatures drop below 50°F at night. Pre-positioning traps in October catches the first wave before populations establish indoors.
November — Rodent and Final Exclusion
- Inspect crawlspace entry and foundation perimeter for rodent entry gaps — Walk the foundation with a flashlight after the first frost when mice are actively seeking warm entry. Seal any gap larger than 1/4 inch with steel wool and foam or hardware cloth.
- Move firewood away from the structure — Firewood stored against the foundation provides rodent harborage and overwintering insect habitat immediately adjacent to the house. Relocate to a rack at least 20 feet from the structure.
- Clear leaf litter from the foundation zone — Accumulated leaf litter against the foundation retains moisture and provides insect and rodent harborage through winter. Remove from a 12-inch perimeter around the foundation.
- Check garage door bottom seal — The rubber seal on the bottom of garage doors is a primary rodent entry point when it hardens, cracks, or fails to seat fully on uneven concrete. Replace worn seals before winter.
- Remove outdoor bird feeders or accept the rodent tradeoff — Seed spillage under feeders is among the most reliable mouse attractants in suburban Missouri yards. If feeders remain, snap traps at the base of the feeder post are warranted through winter.
D&D Pest Control provides fall and winter pest management programs for Franklin County and rural Missouri — visit ddpestcontrolmo.com.