How Climate Change Is Stretching Europe’s Insect Season

Q: Are ticks active in winter now?

Ixodes ricinus becomes active on mild days once ground temperatures rise above roughly 5–7 °C, so scattered winter activity is normal in much of western and central Europe.

Q: Is the Asian tiger mosquito now in central Europe?

Yes. ECDC vector surveillance records established Aedes albopictus populations across large parts of southern Europe, with expanding footholds in Switzerland, Austria and Germany.

September 18, 2026

Walker on a misty European woodland trail in warm late-autumn light, illustrating Europe’s lengthening mosquito and tick season

Key takeaways

Europe is warming faster than any other continent, and the season in which biting insects are active has stretched at both ends — earlier in spring and later into autumn.
Ticks are the clearest example: Ixodes ricinus can quest for a host on any mild day, so there is no longer a reliable winter off-switch in much of western and central Europe.
Mosquitoes benefit from warmer nights and longer warm spells, and the Asian tiger mosquito (Aedes albopictus) has established itself across large parts of southern and central Europe.
Practical upshot: protection is no longer a July–August habit. Treat April to October as bite season, and keep a repellent in the bag on mild winter walks.
Choose a repellent you will actually reapply. incognito® uses PMD (Citrepel®), a plant-derived active, and is DEET-free, vegan and biodegradable.

Ask most people in Germany, Austria or the Czech Republic when insect season starts and they will say May, ending some time in August. That mental model is increasingly out of date. Warmer springs, milder winters and longer autumn warm spells have widened the window in which mosquitoes, ticks and biting flies are active — and in some regions have added species that were not there twenty years ago.

What is actually changing

According to the Copernicus Climate Change Service and the World Meteorological Organization, Europe is the fastest-warming continent, heating at roughly twice the global average since the 1980s. For biting insects, three consequences matter more than the headline temperature:

Earlier spring warmth. Development from egg or larva to biting adult is temperature-driven. A warm March pulls the first generation forward by weeks.
Milder winters. Fewer hard frosts mean better overwintering survival for both eggs and adults, and more mild days on which ticks can be active.
Longer, warmer autumns. September and October now routinely deliver the kind of warmth that used to end in late August, extending the last generations of the year.

Rainfall pattern matters too. Mosquitoes need standing water, so a wet spring followed by a hot summer often produces a worse mosquito year than a uniformly hot, dry one.

Then and now: how the season has shifted

Element	The old mental model	What people report now
Tick activity	April to September	Any mild day above roughly 5–7 °C, including February and November
Mosquito peak	June to August	May to early October, with autumn flare-ups after warm, wet spells
Wasps	Late summer nuisance	Same peak, but colonies often persist further into October
Tiger mosquito	A Mediterranean holiday problem	Established populations in parts of Italy, France, Spain, Switzerland, Austria and Germany
Repellent habit	Packed for holidays	Year-round item for anyone who walks in grass or woodland

Ticks lost their off-season first

The castor bean tick, Ixodes ricinus, is the main vector of Lyme borreliosis and tick-borne encephalitis (TBE) in Europe. It does not need summer heat — it needs humidity and a ground-level temperature above roughly 5–7 °C. Mild, damp winters therefore produce scattered activity right through the cold months, and European Centre for Disease Prevention and Control (ECDC) maps show Ixodes ricinus established across almost the whole continent, including at altitudes and latitudes that were previously marginal.

This is why the autumn peak surprises people: a second seasonal rise in tick activity in September and October is normal, and it lands exactly when families head into the woods for mushrooms and half-term walks.

Mosquitoes: more generations, new species

Warmth speeds up the mosquito life cycle, so a longer warm season means more generations per year rather than simply bigger individuals. It also shifts which species can survive. ECDC vector surveillance now records Aedes albopictus, the Asian tiger mosquito, as established in large parts of southern Europe with expanding footholds further north — a species that bites aggressively during the day, unlike the dusk-and-dawn Culex mosquitoes most Europeans grew up with.

The public-health consequence is that locally acquired cases of dengue and chikungunya, once purely travel-imported, now occur in European summers, and West Nile virus circulates in several countries each year. These remain uncommon relative to the number of bites people get, but they are the reason surveillance has intensified.

What this means for how you plan the year

February–March: tick checks after mild-day walks. Not every winter walk, but any day that feels like spring.
April–May: first real mosquito emergence in most of central Europe; the point to restock rather than to start shopping.
June–August: peak for nearly everything, plus wasps from late July.
September–October: the underrated window — a second tick peak, late mosquito activity and lingering wasps.
November–January: low risk, not zero risk. Keep one repellent where you keep the walking boots.

If you want the autumn detail, we covered it separately in whether you still need repellent in autumn, and the northward spread of the tiger mosquito in our guide to Aedes albopictus in Germany.

Prevention that still works, whatever the season does

Cover skin where you can. Long, light-coloured clothing and tucked socks in tick habitat remain the cheapest intervention.
Apply repellent to exposed skin and reapply according to the label — a repellent only works for as long as it is on you.
Check for ticks within a few hours of being in long grass or leaf litter, including the scalp, behind the knees and the waistband.
Remove standing water around the house: saucers, gutters, buckets and toys are where tiger mosquitoes breed.
Screen bedrooms in high-mosquito regions rather than relying on repellent overnight.

How incognito® helps

A longer season means more days of application, which makes what is in the bottle matter more. Our Insect Repellent Spray is built around PMD (Citrepel®), a plant-derived active from Java citronella (Cymbopogon winterianus) — the same class of active that CDC and EPA list alongside DEET for skin-applied repellents. It is DEET-free, clinically tested, vegan and biodegradable, and recommended against both mosquitoes and ticks. For children, the Kids Insect Repellent Spray is the version to reach for; always follow the age guidance on the label rather than a general rule of thumb.

We are DEET-free for a practical reason as much as an environmental one: a repellent that does not attack plastics, sunglasses or watch straps is one you are more likely to keep using through a season that now runs half the year.

FAQs

Is insect season really getting longer in Europe?
Yes. Warmer springs, milder winters and longer autumn warm spells have widened the window in which mosquitoes and ticks are active, and Europe is warming at about twice the global average.

Are ticks active in winter now?
Ixodes ricinus becomes active on mild days once ground temperatures rise above roughly 5–7 °C, so scattered winter activity is normal in much of western and central Europe.

When should I start using insect repellent each year?
Treat April as the practical start for mosquitoes in central Europe, and carry protection on any mild-weather walk in tick habitat from late winter onwards.

Is the Asian tiger mosquito now in central Europe?
Yes. ECDC vector surveillance records established Aedes albopictus populations across large parts of southern Europe, with expanding footholds in Switzerland, Austria and Germany.

Does a warm winter mean a bad mosquito year?
Not on its own. Mosquito numbers depend on rainfall as well as warmth — a wet spring followed by a hot summer usually produces more mosquitoes than a warm but dry year.

Does a longer season mean I need a stronger repellent?
Not stronger — more consistent. Coverage of exposed skin and reapplication according to the label matter more than the highest concentration on the shelf.

Sources

This article is for general information only and is not medical advice. If a bite becomes infected, you develop an expanding rash after a tick bite, or you feel unwell after being bitten, contact your doctor.