Where Do Mosquitoes Go in Winter? How They Survive the Cold

Key takeaways

• Mosquitoes do not migrate south for the winter. In Europe they survive the cold in a dormant state called diapause — either as mated adult females, as eggs or as larvae, depending on the species.
• The common house mosquito (Culex pipiens) overwinters as adult females hiding in cellars, sheds, garages, drains, caves and attics. All males die in autumn.
• The Asian tiger mosquito (Aedes albopictus) and floodwater mosquitoes overwinter as cold-resistant eggs stuck to the walls of containers or in dry soil, ready to hatch when spring rain arrives.
• Below roughly 10 °C most mosquitoes stop flying and biting. A mosquito that bites you indoors in December is usually a hibernating female woken up by central heating.
• Autumn and winter are the best time to clear breeding sites — empty and scrub containers, cover water butts and check cellars — so fewer mosquitoes emerge next spring.

Every autumn the whining stops, and it is tempting to think mosquitoes simply die out with the first frost. In fact, many of the mosquitoes that bite you next summer are already alive — tucked away in a cellar, as eggs in a flowerpot or as larvae in the mud of a pond. Here is where mosquitoes go in winter, how they survive the cold and what that means for you.

Do mosquitoes die in winter?

Most individual mosquitoes do die when the weather turns cold. Adult males live only a few weeks and do not survive the autumn at all. But each species has one life stage that is built to get through winter, and that stage carries the population into the next season.

Mosquitoes are cold-blooded, so their body temperature follows the air around them. As temperatures drop towards 10 °C they become sluggish, and below that most species stop flying, feeding and breeding. Instead of dying, the overwintering stage enters diapause — a pre-programmed dormancy triggered mainly by shorter days and falling temperatures in late summer and autumn.

Three ways mosquitoes survive the cold

1. As hibernating adult females

The common house mosquito, Culex pipiens, is the best-known winter survivor in Europe. In late summer, females that will overwinter mate, stop taking blood meals and feed on plant sugars instead, building up fat reserves. They then look for a sheltered, frost-free spot with stable humidity: cellars, basements, sheds, garages, stables, drains, caves, bunkers and hollow trees. There they sit motionless on walls and ceilings for months, living off their fat.

Some Anopheles and Culiseta species also overwinter as adult females. A few of them, such as Culiseta annulata, may wake up on mild winter days and occasionally look for a blood meal.

2. As eggs

Many Aedes species — including the invasive Asian tiger mosquito, Aedes albopictus — spend the winter as eggs. Females lay them just above the waterline in containers, tree holes or on damp ground. In temperate strains of the tiger mosquito, eggs laid in autumn enter diapause and can survive cold and dry conditions for months. When spring rain and warmth return, they hatch. This is one reason the tiger mosquito has been able to establish itself north of the Alps; our article on the Asian tiger mosquito in Germany explains where it now lives.

Floodwater mosquitoes such as Aedes vexans use the same strategy on a large scale: their eggs lie in the soil of river meadows and hatch in huge numbers after spring floods.

3. As larvae

A smaller group of species overwinters as larvae in water. Coquillettidia richiardii, for example, spends the winter as larvae attached to the roots of reeds and water plants in ponds and marshes, drawing oxygen from the plant tissue. Some tree-hole species, such as Anopheles plumbeus, can also overwinter as larvae in water-filled tree cavities.

How common European mosquitoes spend the winter

Why a mosquito bites you indoors in winter

If you hear a mosquito in your bedroom in December, it is almost certainly a hibernating female that has woken up. Houses with heated cellars, stairwells and flats in apartment blocks are warm enough to break the dormancy. Once awake, she has used up much of her fat and may look for a blood meal.

In some cities there is also an underground form of the house mosquito, Culex pipiens form molestus, which lives in flooded basements, sewers and underground systems. It does not need to hibernate in the same way and can bite all year round in warm buildings. If you are regularly bitten indoors in winter, check your cellar, drains and any standing water in the building.

Our guide on how to keep mosquitoes out of your bedroom at night has practical tips that work in any season.

Can mosquitoes carry diseases through the winter?

Researchers have found that some viruses, including West Nile virus, can persist in overwintering Culex mosquitoes and reappear in the next transmission season. In Europe, West Nile virus infections in people are reported mainly from June to November, and the risk in winter is very low because hibernating mosquitoes rarely bite. Still, it is one reason public health agencies such as the ECDC monitor mosquito populations year-round.

Milder winters also matter. As our article on how climate change is stretching Europe’s insect season explains, shorter and warmer winters let more mosquitoes survive and allow them to become active earlier in spring.

What to do in autumn and winter to reduce mosquitoes next year

1. Empty and scrub containers. Tiger mosquito eggs stick to the inside walls of buckets, watering cans, plant saucers and toys. Tipping the water out is not enough — scrub or rinse the walls, then store items upside down or under cover.
2. Cover water butts and rain barrels with a tight lid or fine mesh.
3. Clear gutters and drains so water does not stand over winter.
4. Get rid of old tyres or store them dry and covered — they are a favourite egg-laying site.
5. Check cellars, sheds and garages. Clusters of motionless mosquitoes on walls and ceilings can simply be vacuumed up.
6. Keep screens in good repair before spring so returning mosquitoes cannot get into the house.

How incognito® helps

At home in the depths of winter you are unlikely to need insect repellent. It becomes useful again on warm autumn evenings, during mild spells, on winter-sun trips and as soon as the first mosquitoes emerge in spring. If you are heading somewhere warm, see our guide to insect repellent for long-haul winter sun.

Our Insect Repellent Spray 100ml is DEET-free and uses PMD (Citrepel®), a plant-based active from Java citronella (Cymbopogon winterianus) — the same class of active the CDC and ECDC list alongside DEET. It is clinically proven, recommended against mosquitoes and ticks, vegan and biodegradable. For a handbag or travel kit, the compact Roll-On Insect Repellent 50ml is an easy option. Always follow the label for application and reapplication.

FAQs

Where do mosquitoes go in winter?
They hide and go dormant. Depending on the species, mosquitoes survive winter as adult females in cellars, sheds and caves, as eggs in containers and soil, or as larvae in ponds and tree holes.

At what temperature do mosquitoes stop biting?
Most mosquitoes become sluggish below about 15 °C and stop flying and biting at around 10 °C. They become active again when temperatures rise in spring.

Why is there a mosquito in my house in winter?
It is usually a hibernating house mosquito that sheltered indoors in autumn and was woken up by heating. In some buildings, an underground form of the house mosquito can also breed year-round in cellars and drains.

Does a cold winter mean fewer mosquitoes next summer?
Not necessarily. Overwintering stages are well protected, and summer mosquito numbers depend much more on spring and summer rainfall and temperature than on how cold the winter was.

Do tiger mosquito eggs survive the winter?
Yes. In temperate regions the Asian tiger mosquito lays diapausing eggs in autumn that can survive cold conditions for months and hatch in spring, which is why scrubbing out containers in autumn helps.

Sources

• ECDC — Mosquito factsheets
• ECDC — Aedes albopictus factsheet for experts
• ECDC — West Nile virus infection
• ECDC — Protective measures against mosquitoes
• WHO — Vector-borne diseases fact sheet
• CDC — Preventing mosquito bites
• NHS — Insect bites and stings

This article is for general information only and is not medical advice. If a bite becomes very swollen, painful or infected, or you develop a fever, speak to a doctor or pharmacist.