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December in a New Hampshire yard
Daniel Brady · NH-Licensed Pesticide Applicator · License #782664
Reviewed by Daniel Brady

What Pests Are Actually Active in December in New Hampshire?

QuietAlmost nothing changed. That’s the answer, not a gap.
December is one of the quietest months on this calendar: only two species are at genuine peak, cockroaches and squirrels, while nine others are winding down at once. Neither peak is really a December event — German cockroaches breed indoors year-round regardless of season, and squirrels are simply back in their late-winter breeding cycle. Outdoors, the pest year is essentially over. There is little worth doing this month beyond routine indoor sanitation, and saying so plainly is the honest answer.

December at a glance

  • Species at peak: 2
  • Turned up: 3 newly active
  • Turned down: 9 winding down
  • The floor: 5 here year-round
Where in the year

You are here · December

A pest year has a shape. This strip is the whole of it — the season you’re in, the months on either side, and the one you’re reading now.

The New Hampshire pest year
WinterYou are here · Dec
This monthSame seasonOther months2 at peak this month
Previous monthNovemberNext monthJanuary
The changelog

What changed in December

Not a list of seven pests re-served every month. A release log: what turned up, what wound down, what’s always here, and what isn’t here at all — 2 species at peak this month.

Turned up

newly active — more than last month

3
cockroachesPeak

Heated homes sustain year-round German cockroach populations. December's 'peak' reading is really the absence of competing outdoor activity, not a new indoor event.

Nothing worth doing this month.

cricketsActive

Only indoor-only activity remains: camel crickets in basements and house crickets near warmth. Field crickets outdoors are gone for the year.

Nothing worth doing this month.

squirrelsPeak

Late-winter breeding resumes, and squirrels may hole up in the drey during extreme cold rather than range widely.

Nothing worth doing this month.

Turned down

winding down — you can stop worrying

9
antsDormant

Colonies are overwintering. Only an indoor nest produces sightings, and usually only on warm days.

Nothing worth doing this month.

batsDormant

Bats are hibernating for the winter. This is genuine hibernation, not simple dormancy, and colonies should not be disturbed.

Nothing worth doing this month.

beetlesDormant

Asian lady beetles are clustered in wall voids; furnace heat may cause the occasional indoor appearance, but there is no new entry happening.

Nothing worth doing this month.

bugsDormant

Boxelder bugs and stink bugs are clustered in wall voids for the winter; furnace heat can prompt occasional indoor appearances.

Nothing worth doing this month.

miceActive

Winter nesting and continued indoor breeding, a step down from November's peak now that the entry surge is long over.

Nothing worth doing this month.

mitesDormant

Clover mites overwinter as eggs and chiggers are gone entirely; only indoor dust mites persist.

Nothing worth doing this month.

raccoonsDormant

Raccoons are in deep torpor bouts, with only occasional foraging on warm nights.

Nothing worth doing this month.

ratsActive

Established indoors for winter, a step down from November's peak now that the entry itself is finished.

Nothing worth doing this month.

spidersDormant

Indoor house spiders remain quiet and hidden; outdoor species are dormant or overwintering as eggs.

Nothing worth doing this month.

The floor

here every month — not this month’s news

5

These are in and around New Hampshire homes every month of the year, December included. They are not December news, and any calendar that lists them as December's pests is padding a list. We know, because ours did.

  • birds

    Roosting and nesting-adjacent nuisance in and around structures runs year-round; peak use of sheltered structure roosts in December is a detail, not a new problem.

  • fleas

    Fleas ride the host. The outdoor stages go dormant with the cold, but a heated home remains a flea habitat in every month of the year.

  • moths

    Pantry and clothes moths breed on stored food and fabric inside a heated home, a climate that does not change from month to month.

  • opossum

    Opossums remain active in every month of the year, including December; brief den stays during extreme cold do not stop them from needing to forage to survive.

  • ticks

    Adult blacklegged ticks quest on any winter-thaw day above freezing — never fully gone, just quiet, which is why they never fully leave this calendar.

Not here

our own old page said otherwise

2

  • Black Rat

    Our old claim: Our own legacy December page listed the Black Rat — and so did the other eleven months, usually first.

    The black rat (also called the roof or ship rat, Rattus rattus) is not established in New Hampshire. Its documented US range is warm and coastal — the lower East Coast, the Gulf States, the Pacific Coast and Hawaii — and in cooler regions it was displaced by the larger, more cold-tolerant Norway rat. We are saying not established rather than never recorded: isolated cargo introductions are documented elsewhere in the country, and we could not verify an occurrence count for this state. The honest claim is that there is no established population here.

    Internet Center for Wildlife Damage Management — roof rat range (icwdm.org)

    What you actually have: The Norway rat (Rattus norvegicus). If you have a rat in New Hampshire in December, that is the one, established indoors for winter.

  • Boxelder Bugs

    Our old claim: Our own legacy December page listed boxelder bugs as a prevalent pest, alongside every other month of the year.

    In December, boxelder bugs are already hidden and dormant in wall voids for the winter. Furnace heat can occasionally prompt an indoor appearance, but that is an incidental wandering, not an active event — the real boxelder-bug stories are the fall entry (September-October) and the spring emergence (April).

    UNH Cooperative Extension — Boxelder Bug fact sheet (extension.unh.edu)

The bottom line — a quiet month
Quiet — 2 species at peak, and that's the whole story

In December there is essentially no outdoor pest activity in New Hampshire. The only pests of note are indoor species that live in heated buildings year-round — and December isn't really about them either, it's just the month nothing else is left to compete with them.

The calendar behind the calendar

Seasonal anchors

The sourced New Hampshire dates and thresholds that actually move the pest year — frost, moratoria, surveillance windows.

  1. 01

    Adult blacklegged (deer) ticks can still quest during winter thaws whenever the temperature rises above freezing and snow cover is absent.

    It's the one exception to December's near-total quiet: 'winter' does not mean 'zero tick activity,' just activity limited to occasional mild days.

    UNH Cooperative Extension — ticks in New Hampshire (extension.unh.edu)

The full picture

December, in plain terms

01

The year closes the way it opened

December's two peak species — cockroaches and squirrels — are the same pairing January opens with, and for the same reasons: German cockroaches breed year-round indoors regardless of season, and squirrels are back in their late-winter breeding cycle. Nine other species are winding down at once, from dormant ants and beetles clustered in wall voids to raccoons in deep winter torpor. Outdoors, the pest year is essentially over. That repetition — the same quiet answer December and January both give — is exactly the kind of honest, undramatic finding a real calendar produces and a flattened, same-seven-pests-every-month list never could.

The short version

Key takeaways

  • 01Only two species are at genuine peak in December: cockroaches and squirrels, both tied to indoor heat or winter denning rather than a new seasonal event.
  • 02Nine species are winding down at once — the outdoor pest year is essentially over.
  • 03Boxelder bugs are already hidden and dormant in wall voids this month, not an active December pest despite the old calendar's listing.
  • 04There is little seasonal action worth taking in December beyond routine indoor sanitation.

Indoor cockroach problem this winter?

December's only real pest story is indoors. We serve southern and central New Hampshire from Manchester.

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Common questions

Follow-up questions

The other half of this calendar

Already know what you’re dealing with?

This page is month-first — it answers “what changed in December?” Every species named here also has a species-first page in the timing guide: the same sourced facts, the full year, one species at a time. If you already know what you’re dealing with, that’s the faster route.

  • NH-licensed applicator · #782664
  • Same-day service
  • Family-owned since 2017

Jump to a species

Sources & references

  1. UNH Cooperative Extension — Boxelder Bug fact sheet

    Boxelder bugs overwinter dormant in wall voids through the winter after the fall entry; occasional furnace-driven indoor wandering only

    extensionverified 2026-07-17
  2. UNH Cooperative Extension — Kitchen Pests fact sheet

    German cockroaches breed year-round indoors in heated buildings with no winter slowdown

    extensionverified 2026-07-17
  3. Internet Center for Wildlife Damage Management — roof rats

    Roof rat (Rattus rattus) US range is the lower East Coast, Gulf States, Pacific Coast and Hawaii; most of the interior is free of roof rats

    extensionverified 2026-07-17
  4. UNH Cooperative Extension — ticks in New Hampshire

    Adult blacklegged ticks can quest during winter thaws above freezing with no snow cover

    extensionverified 2026-07-17

Editorial disclaimer: This content is provided for informational purposes only and does not constitute pest control or medical advice. Every property is unique — consult a licensed professional for guidance specific to your situation. Anchor Pest Services is licensed in New Hampshire (#782664).

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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Last updated Jul 2026

The quiet month

We'll tell you when there's nothing to do

December has no broad outdoor pest problem to solve. Same-day service available across southern and central NH for the indoor exceptions.

Get a Free Inspection(603) 785-0118
  • Family-owned in Manchester since 2017
  • NH commercial applicator #782664, category F1
  • We will tell you when the answer is to do nothing

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