At a glance
Pests enter basements and garages chasing moisture, warmth, and winter shelter, not to attack your house. Most of what comes in causes zero damage; a few species can stain if crushed, and rodents are the one genuine exception, covered elsewhere on this hub.
One shared severity track, two markers. The span between them is the hype delta — named out loud.
That every pest coming into a basement or garage is invading to threaten the home — treating a silverfish or a boxelder bug with the same urgency as a termite or a rodent.
Where the claim comes from: Pest-marketing blogs that frame all basement and garage entries as an equally serious property threat to sell a blanket treatment.
The documented driver is behavioral, not destructive. Moisture-dependent arthropods lack the physiology to conserve water and are drawn to damp basements as an indicator of dampness, not an attack. Overwintering insects enter diapause — seasonal dormancy — and seek a temperature-stable void to survive winter, triggered by dropping fall temperatures; they don't feed, breed, or lay eggs indoors. None of this group damages a structure. Rodents are the one genuine exception and are a separate, well-documented damage class covered on this hub's gnawing and wiring pages.
They're not invading to wreck your house — they're chasing humidity and warmth, the same way you'd put on a coat. The bug is a clue about your building envelope, not a structural threat.
Moisture-dependent arthropods like sowbugs lack a waxy cuticle layer or spiracle-closing mechanism to conserve water, so they physiologically require high humidity and are drawn to damp basements and garages as an indicator of dampness, not as an attack on the building. Overwintering insects enter diapause — a seasonal dormancy triggered by dropping temperatures and shortening days in fall — and seek a protected void to wait out winter; they don't feed, breed, or lay eggs indoors, and most try to leave again in spring. Neither group has any chewing, boring, or excavating behavior directed at the structure itself. Rodents are the genuine exception: they enter the same spaces for warmth and food, and once inside they gnaw plastic, wiring, and stored goods — a fundamentally different mechanism covered on this hub's gnawing and wiring pages.
Assessed from: UMN Extension — Boxelder Bugs; UMN Extension — Springtails; University of Maryland Extension — Springtails
Scope, not dollars — the honest answer to “how expensive is it,” routed to the right trade.
For the moisture-indicator and overwintering insects, sealing entry gaps and reducing dampness is a homeowner-grade fix — there's no material damage to repair, just entry points to close and humidity to manage. Rodents are the exception and need exclusion, which is pest work.
Anchor does the exclusion and perimeter sealing that keeps rodents and overwintering insects out — genuinely Anchor's lane, and a fall treatment ahead of first frost reduces overwintering entry. Anchor does not fix the underlying moisture, grading, or foundation defect that draws pests in, and doesn't handle moles, voles, or chipmunks — those are landscape and wildlife matters.
Pests entering a basement or garage are responding to one of three specific drivers: moisture, temperature refuge, or seasonal shelter. None of these is 'invading to threaten the home,' and the distinction matters, because the fix for a moisture-driven visitor is completely different from the fix for a rodent looking for food and warmth. Treating every basement bug the same way misses the actual, documented behavior behind each one.
Silverfish, springtails, camel crickets, sowbugs and pillbugs, and centipedes show up in damp basements because many of them physiologically require high humidity to survive — sowbugs, for instance, lack the waxy cuticle layer and spiracle-closing mechanism most insects use to conserve water. Their presence isn't an attack; it's closer to a smoke detector for dampness. None of them chew, bore, or degrade any building material, and centipedes are even a mild net positive as predators of other small pests. If you're seeing a lot of them, the useful move is checking for a moisture source, not spraying the bugs and calling it solved.
Cluster flies, boxelder bugs, brown marmorated stink bugs, and multicolored Asian lady beetles enter homes and outbuildings in fall specifically to survive winter. They enter diapause, a seasonal dormancy, triggered by dropping temperatures and shortening days, and they seek a protected void — a wall cavity, an attic, a garage corner — to wait it out. Critically, they don't feed, breed, or lay eggs indoors during this period, and most try to leave again once temperatures warm in spring. The only property-adjacent consequence is a stain if one is crushed rather than vacuumed, and even that is a rare, minor cosmetic event rather than damage in any structural sense.
Mice and rats enter basements and garages for the same broad reasons — shelter and temperature — but their behavior once inside is fundamentally different. Rather than waiting dormantly, they actively seek food, build nests, and gnaw plastic, wiring, insulation, and stored goods as obligate incisor maintenance. This is a genuinely different damage class, covered in depth on this hub's gnawing, wiring, and building-systems pages, and it's the one scenario in this list where exclusion — not just sealing a gap — is worth treating as pest control rather than a weekend project.
Southern and central New Hampshire's overwintering-insect entries track fall's cooling trend closely, with activity picking up as overnight temperatures approach Manchester's first hard frost — historically around October 19 to 29, per NOAA. Rodent pressure follows the same seasonal curve for a different reason: as outdoor food and shelter disappear, mice and rats push toward the same basements and garages, which is why a fall perimeter check and seal — ahead of first frost — catches both problems before a full winter of activity accumulates.
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We seal the entries that let rodents and overwintering insects in — a fall perimeter treatment ahead of first frost handles both.
Overwintering behavior; boxelder bugs enter in fall, don't reproduce indoors, and stain when crushed
Springtails are harmless moisture indicators; large numbers signal high moisture
Springtail infestations are associated with dampness and organic matter, and serve as a moisture indicator
Moisture and fungal growth sustain springtail populations; the insects themselves are harmless
Written & reviewed by
VerifiedDaniel 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.
Last updated Jul 2026
Honest pest help for New Hampshire homes
Most basement and garage invaders — silverfish, springtails, boxelder bugs — cause no damage at all and just need sealing and moisture control. Anchor Pest Services handles the perimeter defense and rodent exclusion that stops the one genuine exception. Family-owned since 2017, NH license #782664, serving Manchester, Nashua, Concord and nearby towns.
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