Where Do Mosquitoes Go in the Winter? Here's the Answer

Most mosquitoes do not leave, and they do not all die. Once it drops below 50 degrees Fahrenheit (about 10°C) they stop flying and go dormant. Depending on the species, they spend winter as adult females tucked into drains, sheds, basements or woodpiles, or as eggs and larvae waiting for warm water in spring.

That short version comes from U.S. Army public health entomologists and the Contra Costa Mosquito and Vector Control District in California. One morning there is frost on the grass, the patio chairs are folded, and the evening air is finally still. Here in Canada, that quiet stretch is one of our favorite parts of the year. So where did they all go?

Where do mosquitoes go in the winter? The short answer

According to the U.S. Army's Defense Health Agency public health entomologists, many people "might be surprised to know mosquitoes don't all die in the winter." Instead, many go dormant. The overwintering spots they list are "underground sewer drains, sheds, garages, basements, inside logs, woodpiles and animal burrows," and the mosquitoes "will tend to rest on the sides of the walls of these sheltered locations."

The Contra Costa district adds caves, culverts and underground storm drains to that list. Other mosquitoes skip the hiding place altogether and spend winter as eggs or larvae. Which strategy a mosquito uses depends on its species, and that is where things get interesting.

What happens to mosquitoes in the winter when it gets cold

Mosquitoes "are cold-blooded insects and cannot regulate their body temperature," the Army entomologists explain. As the weather cools, adult mosquitoes "will become lethargic." Then, "when temperatures reach below 50 degrees Fahrenheit, the mosquitoes will stop flying altogether."

Before that point, the Army team notes, females do one of two things: they lay their final eggs, or they go looking for "the warmest spot to overwinter." Vector Disease Control International (VDCI) puts the practical result simply: "mosquito bites during winter all but stop once it dips below 50°F."

Diapause and quiescence: the two ways they wait it out

Entomologists describe two kinds of dormancy, and the difference is all about timing.

Diapause: planned in advance

Diapause is a biologically controlled pause that starts before harsh conditions arrive. In the Army's description, blood-feeding females slow their metabolism and pause their development until warmer temperatures return. In some species, diapause happens in the larval stage instead. The Contra Costa district calls it a kind of hibernation, and describes adult females heading for shelter ahead of the coldest weeks.

Researchers Denlinger and Armbruster, in a 2014 review in the Annual Review of Entomology, describe diapause as a mechanism "for bridging unfavorable seasons in both temperate and tropical environments." They also note it "appears to have evolved independently numerous times" in mosquitoes, which is why closely related species can pause at very different life stages.

Quiescence: an immediate reaction

Quiescence is an on-the-spot response to conditions. Here the adult female dies, but her dormant eggs "hatch by submergence in warmer water when the temperature rises," per the Army entomologists.

One more detail we love: dormancy can occur in every life stage of the mosquito "except the pupae."

Winter by mosquito type

None of the pages we read laid this out in one place, so here it is. Each row comes straight from the source named in the last column.

A few notes on that table:

• The hiders. In Contra Costa County, the district says Culex and Anopheles females look for shelter "in late October or November" and stay there "until the first sign of warmer weather, often in late February or early March." Those dates are for that California county, so your local timing will differ.
• The egg savers. The Army entomologists say Aedes eggs laid in soil in flood areas "can remain dormant for as long as two years." The Contra Costa district describes "installment hatching," where not every egg hatches after one flooding and "some may remain dormant for several years." As the district puts it, "even mosquitoes know not to put all their eggs in one basket." The CDC adds that Aedes eggs can survive drying out for up to 8 months.
• The slow growers. The tree-hole mosquito spends most of the winter as larvae, which emerge as adults with warm spring weather, usually in April or May in Contra Costa County.
• The odd one out. The "winter mosquito," Culiseta inornata, flips the script. The district says it is "most active during the winter months and absent or rare during the summer." These are their largest mosquitoes and "will sometimes bite people, although they are not known to transmit disease and generally don't fly far from where they emerged."

Do mosquitoes die in winter?

Some do, and the population carries on anyway. In quiescence, the adult female dies but her eggs wait for warm water. In diapause, the adult females survive by slowing everything down. Either way, the next generation is ready for spring.

If you have wondered where male mosquitoes go, the sources we used focus on females. In species like Culex, it is the adult females that overwinter in shelters, according to the Contra Costa district.

Why is there a mosquito in my house in winter?

You are reading on the couch in January and there it is, drifting past the lamp. A few possible reasons, all from the sources above:

1. It was overwintering nearby. Basements, garages and sheds are on the Army entomologists' list of sheltered spots where adult mosquitoes rest on the walls through the cold months. A warm house is next door to all three.
2. You live somewhere mild. VDCI notes that dormancy is "more common in higher latitudes and areas with significant seasonal variation, so communities in milder climates may see some activity continue during warm spells."
3. It is a winter specialist. In some places, like Contra Costa County in California, the winter mosquito Culiseta inornata is most active in the colder months.

If a stray one keeps you up, our guide to keeping mosquitoes out of the bedroom and other rooms covers the indoor side.

Where it is still mosquito season this winter

Here is the happy flip side of a quiet northern winter: somewhere else, it is summer.

Australia. Under the Bureau of Meteorology's calendar definition, as Weatherzone explains, Australian "Summer = December to February." That means beach evenings, campsites and long walks right through our winter holidays. If you are heading south, our Australian summer repellent guide walks through how to choose by active ingredient, strength and trip.

The southern United States. The CDC notes that Aedes eggs "can even survive a winter in the southern United States," and VDCI says milder climates can see some activity during warm spells. A winter escape to somewhere warm is still worth packing for.

Packing tips. The CDC lists these active ingredients for EPA-registered insect repellents: DEET, picaridin (icaridin), IR3535, oil of lemon eucalyptus (OLE), para-menthane-diol (PMD) and 2-undecanone. The CDC also advises: "If you are using sunscreen, apply sunscreen first and insect repellent second." Flying? Here is how to handle bringing bug spray on a plane under TSA rules.

For warm-weather trips, we made Bloc Off spray with 8% PMD derived from lemon eucalyptus, in an alcohol-free, water-based formula. My co-founder Cassidy Huang and I spent two years with a Taiwan-based chemist developing it. It belongs in a beach bag or a summer travel kit, wherever mosquitoes are actually flying.

A winter to-do list for an easy spring

Winter is the calm, low-effort window to set up a better spring. The Army entomologists point out that "all mosquitoes require water to breed" and can develop "in water sources as small as a teaspoon," which makes fall and winter a good time to remove breeding sites. On a mild weekend, check these spots from their list:

• Clogged gutters
• Saucers under potted plants
• Tarps that collect rain
• Tree holes
• Birdbaths (drain, scrub and refill, or store for the season)
• Corrugated downspout pipes
• Drip pans under window air conditioners
• Any other containers that hold water, like buckets, toys or empty pots

Why now? In spring, VDCI notes, the mosquito life cycle "depends on water, which becomes abundant through melting snow and spring showers." And once water is back, the CDC says Aedes go from egg to adult in about 7 to 10 days. Draining those spots before the thaw means your first patio evening of the year is a good one.

When the warm weather does arrive, the Army team's personal protection basics are simple: long sleeves and long pants, plus an EPA-approved repellent on exposed skin, used as directed, because "The label is the law."

FAQ

Do mosquitoes die in the cold?

Not all of them. U.S. Army entomologists say they slow down as it cools and stop flying below about 50°F. Some adult females die and leave dormant eggs behind, while others wait out winter in diapause in sheltered spots.

Can you get mosquito bites in winter?

It is uncommon. VDCI says "mosquito bites during winter are uncommon once temperatures dip below 50°F," though milder climates may see some activity during warm spells. In some areas, like Contra Costa County in California, the winter mosquito Culiseta inornata is active in winter and "will sometimes bite people."

How long can mosquito eggs survive the winter?

It depends on the species. U.S. Army entomologists say floodwater Aedes eggs can stay dormant "for as long as two years," and the Contra Costa district says some "may remain dormant for several years." The CDC says Aedes eggs can survive a winter in the southern United States.

When do mosquitoes come back?

When the weather warms and water returns from melting snow and spring rain. In Contra Costa County, the district says overwintering Culex and Anopheles females often emerge in late February or early March. Timing varies a lot by region, so check with your local mosquito control district or health department.

Where do mosquitoes go in the winter in Canada?

They use the same strategies: dormant adult females in sheltered spots, and dormant eggs or larvae waiting for spring water. VDCI notes that dormancy is "more common in higher latitudes and areas with significant seasonal variation," which describes much of Canada, so expect a long, quiet winter on the patio.

Written by Tanya Lee, Co-Founder of The Superbloc. Sources: U.S. Army / Defense Health Agency Public Health, "Where Do Mosquitoes Go During The Winter?" (2025); Contra Costa Mosquito and Vector Control District, "Where Do Mosquitoes Go in Winter?"; CDC, "Life Cycle of Aedes Mosquitoes" and "Preventing Mosquito Bites"; Vector Disease Control International, "Where Do Mosquitoes Go in the Winter?"; Denlinger DL, Armbruster PA, "Mosquito diapause," Annual Review of Entomology (2014); Weatherzone, "When does winter start?"