Mosquitoes hibernate in winter

Contrary to many opinions, mosquitoes (Nematocera) hibernate, although not all. This mainly depends on their gender and the respective stage of development. While the males die in autumn, the females prepare for winter from around mid-October. By then they have already laid their eggs, which, together with the larvae, are waiting for the next summer even in the icy cold. Sometimes people are not safe from a mosquito bite even at sub-zero temperatures. The following explains how and why mosquitoes spend the winter.

Winter myth

It is often assumed that mosquitoes only survive in warm climates. This is due to the fact that the number of Nematocera usually decreases significantly in autumn. This is also true so far, but that is because the male mosquitoes die and only the female specimens remain. These are also the ones who sting. While the male animals feed themselves purely on plant sap, the females need additional protein, especially after fertilization, which they suck up from human or animal blood.

In Siberia, the female mosquitoes even survive temperatures below 50 degrees Celsius in some places. To do this, depending on how mosquitoes develop, they have different strategies to survive the cold season alive so that they can actively search for food again in the following spring.
The number of biting insects is therefore less dependent on the cold outside temperatures, but more on the spring. The more humid it is, the more they multiply and buzz en masse through the summer and Germany's gardens or apartments.

wintering

The mosquitoes have three strategies that allow them to survive the winter even in extremely sub-zero temperatures:
  • than eggs
  • as larvae
  • than female adult mosquito
In the last act of the male mosquitoes living in late summer or autumn, they fertilize the females. These usually lay their eggs where the larvae that develop from them are able to survive in winter.

Eggs and larvae have excellent chances of survival in winter, as they hardly offer any surface for frostbite due to their low water content in winter. Afterwards the adult mosquitoes go in search of their suitable winter quarters.

Winter quarters

From autumn the mosquitoes look for a place to hibernate. They prefer cool, dry winter quarters that are safe from predators, which is why they like to use open windows and doors, especially in autumn, to find an optimally suitable wintering place in cellars, garages, cattle sheds or garden sheds. There they fall into winter rigor in cold ambient temperatures. In water, the eggs usually survive the winter cold in the mud or morass of a pond, for example. You will also find optimal winter quarters in rain barrels. Here they are deposited by the mother animals.

The larvae settle below the surface of the water. Their breathing tube extends through the surface of the water and allows them to absorb oxygen even in frozen waters. as long as the ice is created afterwards. But if the water is already completely covered with ice before the larvae can direct their breathing tube upwards, they will not survive long. Otherwise, like the adult mosquitoes, they spend the cold winter months in a frozen state. For the eggs, too, completely frozen water means certain death from a lack of oxygen.

TIP: In order to contain a mosquito plague in the following year, you should let water tanks freeze and, in ponds, simply insert reed tubes that reach almost to the pond floor and that freeze over all around, but provide oxygen to other ecologically valuable animals underwater.

Numbness

If the outside or ambient temperatures drop to five degrees Celsius or less, mosquitoes and their larvae enter the rigid winter stage.

Cold protection
The body of the Nematocera gives the insects special protection that prevents them from freezing to death. As cold-blooded animals, their bodies react to the cold temperatures by also reducing their own body temperature. At the same time, mosquitoes, as they are also known, excrete more body fluids in order to minimize the potential for frostbite. In addition, more water binds with protein, which in turn increases the salt content in the body. In addition, natural protection from the cold is formed in the blood on a glycerine basis, as is also used for water antifreeze, for example in vehicles. This means that the blood cannot freeze, as is the case, for example, with dogs as animals of the same temperature.

Organ functionality
During the freezing winter, organ activity decreases with decreasing body temperature. The body system shuts down evenly to a kind of standby mode and only functions with a minimum of activity so that important organ functions keep the body alive. This also includes the body's mobility, which leads to complete freezing with decreasing ambient temperature. As a result of the shutdown system with flattened heart and breathing rates and the inability to move, little energy is consumed.

Food supply
The mosquitoes take in additional energy for the winter rigor as early as late summer through increased food intake. This is stored in a fat depot, which can be recognized by the yellowing of the rear part. From this, the mosquito body supplies itself with the energy it needs, which enables organ functionality during rigid winter.

Wake up
If the temperatures rise to between eight and ten degrees Celsius, mosquitoes and their larvae wake up again. This costs them additional energy, which prompts them to go looking for food in winter and pursue their stinging for blood here. So it is quite possible that you are not necessarily safe from a mosquito bite in December or January.

It also happens every now and then that mosquitoes do not even fall into the freezing winter because they have chosen a warm winter quarters. As a rule, however, they do not survive the winter season.

TIP: If you warm up closed rooms to over ten degrees Celsius every now and then, you tear the mosquitoes out of their winter rigor. The increasing energy consumption increases the chance that the mosquitoes that hibernate there will no longer piss you in the following year.

End of winter

Depending on how cold or warm the months between February and April are, early spring is the greatest danger for this insect species. It is known that winter can strike once again with icy temperatures at the official beginning of spring and frosty temperatures are possible even up to the ice saints in May. While this is less of a problem for the mosquito eggs, the mosquitoes and their larvae have far more survival problems here. Short, sudden drops in temperature do not allow your body to adjust the temperature evenly once you have awakened from the rigors of winter. This means that your protection against the cold cannot react so quickly to unexpected frosts and the risk of freezing to death increases immensely.

However, this does not apply to mosquito eggs. A sudden frost doesn't bother them because they don't have any water or blood that could freeze.
Since female mosquitoes can lay up to 300 eggs several times in a few days and begin to reproduce in early spring, the mosquito is definitely not threatened with extinction, despite the possibly high death rate due to renewed freezing temperatures after the winter rigor.

Conclusion
Only female mosquitoes and their eggs and mosquito larvae overwinter, while the male conspecifics die before the onset of winter. Most of these insects survive icy temperatures in a winter rigor or the eggs are almost completely frost-resistant. A warm, damp spring offers excellent conditions for masses of these stinging pests, as the overwintered mosquitoes can optimally multiply here. The tips mentioned help to make the winter time more difficult for these females and their offspring in order to prevent or at least significantly minimize the mass reproduction in the following year.