Mosquitoes are clever: They are active all year round sómewhere on the planet. That’s why they are one of the most successful insects on the face of our earth. One of our least favorite bugs just happens to be a ‘survival of the fittest’ winner. What’s more, mosquitoes seem ‘bug’ us all year round. Or do they? I’ve been looking into whether mosquitoes really are an all year round phenomenon in a single location… So if you want to know your enemy, read on!
Mosquitoes are supposed to be a summertime problem. When the weather starts to warm up, we expect them to appear. In swarms. But how true is this? I know I’ve been bitten during the winter months, and I’m sure you have, too. For many of us, mosquitoes seem to be a year-round problem with peak times in warm, humid weather. Perhaps global warming is changing their habits? Or are mosquitoes changing their habits for other reasons? Do warmer mega-cities create winter habitats for mosquitoes? Or have mosquitoes undergone internal changes which allow them to function all year round?
Adult mosquitoes have short lives, so they will not live all year round. Instead, they hibernate below temperatures of 50°F. Most mosquito species fall into diapause during cold weather, but can survive it. Mosquito eggs will survive harsh winters. Mosquito larvae die if frozen for long periods of time.
Do Mosquitoes Hibernate During Winter?
Mosquitoes often go into one of two types of hibernation at adult, larva, or egg stages: quiescence (overwintering) or diapause (suspended development). During mild winters or in large city environments, hibernation times can be shorter or absent. Some mosquitoes are endophilic, preferring indoor life all year round.
It is we humans – or more specifically our transport systems – that have upset the balance of mosquito behavior. In such a highly adaptable insect species, bringing tropical mosquitoes to temperate areas and temperate mosquitoes to tropical or arctic regions has led these pesky creatures to change their behaviors to make them successful anywhere on the planet. Let’s start with looking at the major classes of globe-trotting mosquitoes and their habits:
- Aedes albopictus: Moved from Asia to Europe & U.S. Has evolved and adapted to overwinter in colder climates, where harsher winters had previously killed it off.
- Aedes aegypti: Moved from tropical climates to Europe. Usually killed off during even mild winters, but has become endophilic and survives indoors.
- Aedes japonicus & koreicus: Moved from Asia to Europe & U.S. Very resistant to cold and drought. Adults can be found nearly all year round.
- Anopheles atroparvus: Has stayed in Europe, but has spread. In warmer areas (Spain, Greece), this mosquito species lives all year round as an adult.
- Anopheles plumbeas: Has spread throughout central Asia through to Western Europe and has become an ‘urban’ mosquito as its eggs don’t survive for long at temperatures below freezing.
- Anopheles freeborni: Most common in the colder states of the U.S and Canada, but unlike many other species the female adults still feed on blood during the winter without producing eggs.
- Culiseta alaskensis: Used to freezing cold weather, C. alaskensis usually hibernates. As it moves into warmer regions and as global warming melts the icecaps, this species of mosquito is having shorter and shorter periods of hibernation.
- Anopheles quadrimaculatus: Another common U.S and Canadian mosquito species which continues to feed throughout the winter, but on nectar.
Obviously, I can’t list every species of mosquito. But it is easy to see that as mosquitoes spread to other countries on our planes, trains, boats and cars, they soon learn to adapt to different temperatures and seasons. Some mosquitoes actually prefer to live indoors and even select artificial containers to lay their eggs in, rather than use natural ponds or marshlands. Many have taken to big-city life. They stay active as adults for much longer thanks to two to three degree higher temperatures. As I’ve said many times, mosquitoes are very, very smart.
How Do Mosquitoes Live Through Winter?
If a mosquito species survives through winter by laying eggs which hatch later in warmer temperatures, adult mosquitoes don’t need to live through winter. If the eggs are fragile, pregnant females must live through winter. They survive cold weather by hibernating or resting in sheltered spaces, or by moving indoors.
In warm, humid areas, mosquitoes live and breed all year round. That’s why it doesn’t matter when you plan your visit to the rain-forest (or any tropical forest); you need to protect yourself from getting bitten all year round. In countries which have four seasons, mosquitoes behave differently. They need to be able to survive winter weather in order to be successful. And we all know how successful mosquitoes are! This means all mosquito species have evolved and adapted, either over thousands of years or just a decade, to cope with different weather conditions. They do one of the following during cold weather:
- The entire species dies: Some mosquitoes can’t survive in certain parts of the world due to the weather.
- The adults die: If eggs and larvae are cold-weather resistant, these stop developing in colder temperatures (diapause). Warmer temperatures trigger their development. There’s not much need for adults during the winter.
- All stages live: Female adults will usually overwinter or hibernate (in quiescence) and are already pregnant. Having done their job, the males die after just a few weeks. Eggs and larvae go into diapause.
- Nothing changes: Some cold-resistant mosquitoes which have spread to warmer regions behave like tropical mosquitoes.
- They move indoors: Mosquitoes are becoming more and more endophilic. They like to live indoors. This means they don’t need long periods of hibernation, if any at all. This is why we get bitten indoors, even in the coldest winter weather.
What Month Do Mosquitoes Go Away?
Mosquitoes rarely go away. In the coldest (or driest) months, mosquitoes go into diapause (insect hibernation) or quiescence (a period of low activity). Equatorial mosquitoes remain active all year round. In the Northern hemisphere, outdoor areas are usually mosquito-free between November and early March.
There are peak times for mosquitoes. In the Arctic, huge swarms are expected once the ice begins to melt. This used to be in late May, but with global warming this time has shifted a month earlier, meaning huge swarms of freshly hatched mosquitoes from April on. Only winter winds above 5 miles per hour keep them away. Or a lack of food. If food is scarce mosquito development waits until the caribou herds arrive. Overwintering females will live for an entire year, allowing her to produce multiple batches of eggs. The poor males survive for about eight weeks and never make it through the winter.
Many mosquito species that used to overwinter now ‘partially overwinter’ thanks to their spreading to warmer regions, moves to urban (warmer) places, or global warming. This affects their peak seasons, too. The warmer it is, the more rapidly mosquito eggs and larvae develop, and the more mosquitoes there are. Populations of Anopheles labranchiae, an Italian mosquito, usually peaked between June to September. But the combination of global warming and this particular mosquito’s love of indoor spaces has made a big impact on its winter behavior.
Instead of hibernating between October and March, adults can be found all year round … indoors. Outside, they disappear in December. That’s all. The adults of Anopheles labranchiae are therefore active from January to November. Who’s to say they won’t adapt further and stay with us all year round?
The safest way to answer the question, “When do mosquitoes go away” is to say, “They don’t”. As the earth warms up and as we continue to heat our homes and cities we are creating new, indoor spaces which most mosquitoes love. This means we really should be protecting ourselves and our homes all year round. Whether you prefer to use natural repellents, thick layers of clothing, or the latest technology, there’s plenty of information available on the endmosquitoes.com site.
How Do Mosquitoes Survive The Winter In Alaska?
Adult Alaskan mosquitoes can still be active at temperatures of 40°F or 4.4°C. Alaskan winter temperatures can sink to 5°F or -15°C. In the winter, adult females and their eggs are in a state of hibernation. The eggs hatch into larvae when the ice begins to melt. Mosquito larvae can survive even if this water refreezes.
Alaskan mosquitoes have to deal with extreme temperatures, but they deal with them perfectly. Huge swarms of mosquitoes cover the Alaskan tundra from April through to October. With global warming, you might think that this means they come out a lot earlier. Some mosquito species might, but only in areas where there is enough food. If food is limited larvae won’t develop into adult mosquitoes unless there is food available. Especially in more northern regions where food is scarce, mosquitoes often remain in the larvae phase even if the temperature is perfect. This ensures that adults always have enough food. Clever things, mosquitoes!
Survival Of The Seasons
In the winter, you probably don’t need to worry too much about stopping mosquitoes from coming into the house. You need to worry about the ones that are already inside! These house-loving (endophilic) skeeters can give us a Christmas present we never asked Santa for. And this is happening more and more often as these clever little bugs move in with us.
There are plenty of ways you can reduce their numbers in the wintertime. Natural methods within the home are always the better option as we tend to open our windows less in cold weather. Strong chemicals aren’t the best idea. Have a look through my product overview for some great ideas.
These range from the simple but effective bed net to indoor handheld or plug-in zappers. Peak season might be over, but you only need one mosquito in your home to ruin a good night’s sleep. Get winter-ready and outsmart them all!