How do I keep stink bugs and boxelder bugs out of my house?

Seal exterior gaps around windows, doors, siding corners, and utility penetrations in late summer, before cold weather sends them looking for shelter — never in fall or winter, which traps whatever's already gotten in instead of keeping new arrivals out. Repair torn screens, focus extra attention on south- and southwest-facing walls where they congregate first before working their way inside, and vacuum any that get inside rather than crushing them against a wall or windowsill.

When exactly should I seal against fall invaders in New Hampshire?

Late summer, ideally by late August, comfortably ahead of Manchester's first hard frost in mid-to-late October and the temperature drop that sends these insects looking for winter shelter. NC State Extension is explicit that bug-proofing in fall, winter, or early spring will likely trap insects inside instead of keeping them out — let any indoor bugs emerge and leave on their own in spring, then seal the same gaps before they try to return the following fall.

Does sealing actually stop stink bugs, or do they always find a way in?

Sealing meaningfully reduces numbers but total exclusion isn't realistic, especially on vinyl-sided homes where the panels themselves aren't a tight barrier. The research-backed threshold is a rigid opening around 6 mm — smaller than a quarter-inch — so consistent caulking of that size and larger, done at the right time of year, is genuinely effective even if it isn't perfect.

What attracts stink bugs, boxelder bugs, and lady beetles to a house?

Shelter, not food. As outdoor temperatures drop toward the first frost, these insects seek overwintering sites and congregate on warm south- and southwest-facing walls, where late-day sun keeps the surface a few degrees warmer, before working their way into gaps, soffits, and siding voids. There's no food source to remove indoors — the entire prevention strategy is physical exclusion timed to arrive before they do, not sanitation or bait.

Should I vacuum or crush stink bugs I find indoors?

Vacuum them. Crushing stink bugs, boxelder bugs, and Asian lady beetles releases a distinctive defensive odor and can stain carpet, upholstery, or curtains, while vacuuming removes them cleanly without either problem. Empty the vacuum canister or bag outside right after, since some species can survive briefly inside a bag and simply crawl back out into the house if you leave it sitting indoors overnight.

How do I prevent bed bugs specifically?

Inspect secondhand furniture, mattresses, and couches thoroughly before bringing them inside, use a protective encasement on mattresses and box springs, reduce clutter that creates hiding spots, and keep luggage off the floor and inspected after travel. Bed bugs are excellent hitchhikers that travel on furniture, bedding, and clothing rather than migrating in through gaps, so exclusion sealing doesn't apply to them the way it does to stink bugs.

How do I keep pantry moths like Indian meal moths out?

Inspect flour, grains, cereal, and pet food for larvae or webbing before shelving them, since eggs are sometimes already present at the point of purchase. Freeze susceptible new purchases at 0°F for 4-7 days to kill anything that made it home in the package, and transfer everything into airtight glass, heavy plastic, or metal containers rather than leaving it in original paper or cardboard packaging, which is porous enough for larvae to breach and spread to nearby shelves.

Why do I have sowbugs, pillbugs, or woodlice in my basement?

These are moisture pests, not invaders looking for winter shelter the way stink bugs are — a basement or crawlspace consistently above roughly 60% relative humidity is inviting enough on its own to sustain a population indefinitely. Dehumidifying, fixing leaks, and clearing mulch and debris away from the foundation removes the damp conditions they depend on to breathe and survive, which is a more durable fix than any sealing or spraying attempt would be.

Why can't I fully seal a vinyl-sided house against these invaders?

Vinyl panels are hung loosely by design so they can expand and contract with temperature, which leaves small gaps behind them that let insects slip through regardless of how well you caulk the visible seams and trim. This is a genuine structural limitation, not a sign your sealing effort failed — the honest expectation on vinyl siding is meaningfully fewer invaders after sealing, not zero, so pair the exterior work with vacuuming any that still get through.

PreventionHousehold Pests

Household Pest Prevention: Seal, Store, and Time It Right

TL;DR

This page covers a broader nuisance mix than a single lever can solve: fall overwintering invaders (stink bugs, boxelder bugs, seed bugs) need exterior sealing timed to late summer — rated HIGH-VALUE but strictly timing-dependent, since sealing in fall or winter traps them inside instead. Bed bugs and pantry moths need different levers entirely — inspection and airtight storage — because they hitchhike in rather than migrate seasonally.

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The exclusion threshold
A rigid ~6 mm (roughly 1/4 inch) gap is the practical seal target for stink bugs
NC State Extension, citing Chambers 2019, Journal of Economic Entomology — one adult passed a 7 mm hole, none passed a 3 mm slit.
The timing rule that matters most
Seal in late summer, never in fall, winter, or early spring
NC State Extension — sealing after they've arrived traps them inside instead of keeping them out.
Where they gather before entry
Warm south- and southwest-facing walls
Michigan State University Extension.
Don't crush them
Vacuum instead — crushing stains surfaces and releases odor
University of Minnesota Extension.

The honest verdict

Does this actually work?

HIGH-VALUE across all three sub-groups, but each depends on a different action done at the right time: late-summer sealing for invaders, inspection habits for hitchhikers, and dehumidifying for moisture crawlers. None of it is instant, and using the wrong lever for the wrong pest (sealing against bed bugs, spraying against sowbugs) wastes effort.

Works — High

Evidence: NC State and Penn State Extension document mechanical exclusion, timed to late summer, as the most effective stink bug and boxelder bug prevention, with fall/winter sealing explicitly flagged as counterproductive. EPA confirms bed bugs travel by hitchhiking rather than through structural gaps, so inspection — not sealing — is the relevant lever. Basement humidity above roughly 60% is independently documented as the driver behind sowbug and pillbug presence.

Works when

Exterior sealing for overwintering invaders is finished by late August, before the fall push
Secondhand furniture, luggage, and clothing are inspected before entering the home
New pantry goods are frozen and transferred to airtight containers on arrival
Basement and crawlspace humidity is kept below the level that sustains sowbugs and pillbugs

Fails when

Sealing happens in fall or winter, trapping overwintering invaders inside instead of excluding them
Bed bug prevention relies on sealing gaps instead of inspecting items brought into the home
Pantry goods stay in original porous packaging instead of airtight containers
A damp basement is sprayed instead of dehumidified

At a glance

One page, three different pests, three different fixes

How it works

Moderate DIY

Three different mechanisms cover this group honestly. Exterior exclusion, timed to late summer, denies overwintering invaders a way in before cold weather sends them looking for shelter. Inspection habits — checking secondhand items, freezing new pantry goods, airtight storage — stop bed bugs and pantry moths, which hitchhike in rather than migrate. Basement dehumidification removes the damp conditions sowbugs, pillbugs, and woodlice need to persist.

Vital stats

Time: A weekend for late-summer exterior sealing; ongoing habits for bed bug and pantry moth inspection; dehumidifier setup plus monitoring for moisture crawlers
Best for: NH homes near woods or fields (overwintering invaders), anyone acquiring secondhand furniture or returning from travel (bed bugs), households buying pantry staples in bulk (pantry moths), and damp basements or crawlspaces (sowbugs, pillbugs, woodlice).
Cost: Low for caulk, screening, and airtight containers; moderate for a basement dehumidifier or mattress encasements

This hub groups a genuinely mixed set of nuisance pests under "household pests": fall overwintering invaders (brown marmorated stink bugs, boxelder bugs, elm seed bugs, western conifer seed bugs) that migrate indoors each autumn looking for shelter, plus bed bugs and pantry moths that arrive by hitchhiking rather than by season, plus sowbugs, pillbugs, and woodlice that show up wherever a foundation stays damp. Lumping them into one prevention lever would be dishonest, because they don't share a single cause.

The overwintering invaders are a genuine exclusion-and-timing story: seal the exterior in late summer, before they arrive, and you keep most of them out — seal after they've already moved in for winter and you trap them, guaranteeing a spring emergence indoors instead. Bed bugs and pantry moths don't respond to sealing at all; they need inspection habits (checking secondhand furniture, freezing new pantry goods) because they travel in rather than migrate in. And the damp-loving crawlers — sowbugs, pillbugs, woodlice — follow the same moisture logic as any basement nuisance. This page walks through all three, honestly separated.

Step by step

How to do it

Seal exterior gaps by late summer, while invaders are still outdoors
Caulk cracks around windows, doors, siding corners, utility penetrations, and soffits with silicone or silicone-latex caulk before fall temperatures start dropping.
Caution: Never do this sealing pass in fall, winter, or early spring — you'll trap overwintering insects that are already inside instead of keeping new ones out.
Repair screens and focus on south-facing walls
Tighten or replace window and door screens, and pay extra attention to south- and southwest-facing walls, where stink bugs, boxelder bugs, and lady beetles congregate before entering.
Tip: If your home is vinyl-sided, expect meaningfully fewer invaders after sealing, not zero — panels are hung loosely enough that some insects slip behind them regardless.
Vacuum any indoor invaders — never crush them
Remove stink bugs, boxelder bugs, or lady beetles found indoors with a vacuum, and empty the canister or bag outside immediately.
Caution: Crushing releases an odor and can stain fabric, carpet, or upholstery.
Inspect secondhand items and luggage for bed bugs
Check secondhand furniture, mattresses, and couches thoroughly before bringing them indoors, and inspect luggage and keep it off the floor after any trip.
Tip: A protective mattress and box-spring encasement eliminates many of the hiding spots bed bugs use once they're inside.
Freeze and store new pantry goods to stop pantry moths
Freeze susceptible new purchases — flour, cereal, grains, pet food — at 0°F for 4-7 days on arrival, then transfer them to airtight glass, heavy plastic, or metal containers.
Caution: Original paper or cardboard packaging is porous enough for larvae to breach; it isn't a real barrier on its own.
Dehumidify basements and crawlspaces for sowbugs, pillbugs, and woodlice
Run a dehumidifier in damp basements and crawlspaces, fix any leaks, and clear mulch or debris away from the foundation to remove the moisture these pests depend on.
Tip: A basement consistently above roughly 60% relative humidity is inviting enough on its own — a hygrometer takes the guesswork out of when to run the dehumidifier.
Reduce clutter that hides bed bugs and fabric pests
Declutter storage areas, reduce cardboard box storage in favor of sealed plastic bins, and vacuum regularly to disrupt hiding spots for bed bugs and fabric-pest larvae.
Tip: Fabric-pest larvae can enter cracks under 1/16 inch — sealed bins are a meaningfully better barrier than cardboard.

What you need

Tools & materials

Silicone or silicone-latex caulk
Seal exterior gaps against fall overwintering invaders
Apply by late August, before the fall entry period
Screen repair kit
Tighten or replace window and door screens
Check fit carefully — a loose screen defeats the purpose
Shop vacuum
Remove indoor stink bugs, boxelder bugs, and lady beetles without crushing them
Empty outside immediately after use
Mattress and box-spring encasements
Eliminate bed bug hiding spots on and around the bed
Choose an encasement rated for bed bugs specifically
Freezer (0°F) and airtight containers
Kill pantry moth eggs/larvae and stop reinfestation from porous packaging
4-7 days for susceptible dry goods on arrival
Dehumidifier and hygrometer
Remove the moisture sowbugs, pillbugs, and woodlice need
Target keeping basement/crawlspace humidity below the level that sustains them
Sealed plastic storage bins
Replace cardboard storage that fabric-pest larvae can enter
Especially useful for off-season clothing and stored textiles

Stay safe

Safety first

General
Low risk
Stink bugs, boxelder bugs, elm seed bugs, and western conifer seed bugs don't bite, sting, or damage your home structurally — treat them as a nuisance, not a hazard, and avoid unnecessary pesticide use indoors against them.
Applicator
Caution
Sealing work at soffits and upper walls involves ladder and height risk — use a stable ladder and don't overreach.
General
Low risk
Avoid indoor insecticides for sowbugs, pillbugs, and woodlice — these are moisture pests, and correcting the dampness is the effective fix, not spraying.
General
Caution
Bed bugs don't spread disease, but heavy infestations can cause significant discomfort from bites; a genuine infestation is best confirmed and treated by a professional rather than escalating DIY sprays.

Avoid these

Common mistakes

Why this method fails in practice.

Sealing against overwintering invaders in fall or winter, which traps them inside
Crushing stink bugs or lady beetles instead of vacuuming them
Trying to seal your way out of a bed bug problem instead of inspecting items brought into the home
Leaving new pantry purchases in original paper or cardboard packaging
Spraying a damp basement for sowbugs or pillbugs instead of dehumidifying it

New Hampshire context

Household pest prevention timing in New Hampshire

New Hampshire's sharp fall temperature drop drives stink bugs, boxelder bugs, and their relatives indoors hard, right around the first frost — and older, wood-sided homes near woods or fields see the heaviest pressure. Vinyl-sided homes can't be fully sealed, since panels are hung loosely enough for insects to slip behind them, which is honest context for why total exclusion is never 100%. This page covers the fall overwintering mix plus incidental hitchhikers and damp-loving crawlers; for the year-round indoor moisture pests (silverfish, earwigs, roaches, crickets), see the separate Common Household Pests prevention page — the two are kept deliberately distinct.

Peak season

Late summer through the October frost for overwintering invaders; year-round vigilance for bed bugs and pantry moths

First-frost anchor: Manchester first hard frost ~Oct 19 (50%) / Oct 29 (80%) per NOAA 1991-2020 — seal exterior gaps by late August, well before this date, never after it

Exclusion, inspection, and airtight storage are DIY-legal statewide with no pesticide license required.

Regional extension programs (Penn State, NC State, Michigan State, University of Minnesota) are unanimous on the late-summer sealing window for overwintering invaders — sealing after they arrive is worse than not sealing at all.

This method targets

Pests this applies to

Western Conifer Seed Bug

Brown Marmorated Stink Bug

Clothes Moth

Indian Meal Moth

Woodlouse

When to call a pro

General Pest Control with Anchor

This mixed nuisance-pest group resolves well with the right lever applied at the right time, but a heavy fall invader influx despite sealing, a confirmed bed bug infestation, or persistent basement moisture pests despite dehumidifying usually needs a professional look. Anchor's General Pest Control service identifies which of the three problems you actually have and treats it accordingly.

Call us when…

Overwintering invaders are still getting in heavily despite a completed late-summer sealing pass
You suspect or confirm a bed bug infestation — DIY treatment for an established infestation has a high failure rate
Pantry moths keep reappearing despite airtight storage and freezing new goods
Sowbugs, pillbugs, or woodlice persist despite dehumidifying and fixing leaks
You're not sure which of these pests you're actually dealing with

General Pest Control

free inspection; same-day service across southern and central New Hampshire.

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Keep them out

Seal exterior gaps against fall invaders by late August, never after the season starts
Inspect secondhand furniture and luggage before bringing them indoors
Keep basements and crawlspaces dehumidified to remove the conditions sowbugs and pillbugs need

Common questions

Frequently asked

Sources & further reading(8)

[1]
NC State Extension — FAQs: Brown Marmorated Stink Bug
Late-summer sealing timing, fall/winter sealing risk, exclusion gap threshold citing Chambers 2019
extensionverified 2026-07-13
[2]
Penn State Extension — Brown Marmorated Stink Bug
Mechanical exclusion with caulk as the best prevention method; screen repair guidance
extensionverified 2026-07-13
[3]
Michigan State University Extension — Boxelder Bugs, Asian Lady Beetles, and Cluster Flies, Oh Boy!
South/southwest wall congregation behavior; vinyl siding sealing limitation
extensionverified 2026-07-13
[4]
University of Minnesota Extension — Brown Marmorated Stink Bug
Vacuum-don't-crush guidance to avoid staining and odor
extensionverified 2026-07-13
[5]
EPA — Protecting Your Home from Bed Bugs
Secondhand furniture inspection, mattress encasement, clutter reduction, hitchhiking behavior
govverified 2026-07-13
[6]
Illinois Dept. of Public Health — Clothes Moths and Carpet Beetles
Fabric-pest larvae entering cracks under 1/16 inch
govverified 2026-07-13
[7]
StaySafe.org — Pantry Pests: How to Spot and Stop Stored Food Invaders
Freezing at 0°F for 4-7 days, airtight container storage for pantry moths
industryverified 2026-07-13
[8]
ExterminateK — Professionally Recommended Solutions for Eliminating Moisture Bugs
Basement humidity above ~60% inviting sowbugs, pillbugs, and related moisture pests
industryverified 2026-07-13

Written & reviewed by

Verified

Daniel Brady

NH-Licensed Pesticide Applicator · License #782664 (NHDAMF, RSA 430)

Daniel Brady is the New Hampshire–licensed applicator behind Anchor Pest Services, a family-owned pest control company serving the Manchester area since 2017.

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Anchor Pest Services

When household pests won't quit, we will.

Same-day service across Southern New Hampshire. NH-licensed #782664. Family-owned since 2017. We diagnose the pest, then treat it the right way — with a satisfaction guarantee.

Get a free inspection Call (603) 785-0118

Keep Exploring

Household Pest Prevention: Seal, Store, and Time It Right

Works when

Fails when

One page, three different pests, three different fixes

How it works

How to do it

Seal exterior gaps by late summer, while invaders are still outdoors

Repair screens and focus on south-facing walls

Vacuum any indoor invaders — never crush them

Inspect secondhand items and luggage for bed bugs

Freeze and store new pantry goods to stop pantry moths

Dehumidify basements and crawlspaces for sowbugs, pillbugs, and woodlice

Reduce clutter that hides bed bugs and fabric pests

Tools & materials

Silicone or silicone-latex caulk

Screen repair kit

Shop vacuum

Mattress and box-spring encasements

Freezer (0°F) and airtight containers

Dehumidifier and hygrometer

Sealed plastic storage bins