Mosquitoes, like all insects, are cold-blooded creatures. As a result, they cannot regulate body heat, and their temperature is essentially the same as the temperature of their surroundings. Mosquitoes work best at 80 degrees Fahrenheit, slow down at 60 degrees Fahrenheit, and cannot function below 50 degrees Fahrenheit. Temperatures below 50 degrees Fahrenheit are a signal that mosquito season is over and that these insects had better go dormant to prepare for winter. In tropical regions, mosquitoes are active throughout the year. In temperate climates, adult mosquitoes of some species become inactive with the onset of cold weather and go into diapause to survive winter.
We are familiar with the idea of mammals that hibernate during the winter, but mosquitoes, like many other insects, can enter a phase of inactivity called diapause. Unfortunately, we live under the misconception that mosquitoes give up their lives when it gets cold.
The bad news first: mosquitoes are more than capable of surviving the winter.
Mosquitoes are insects that have been around for a long time, so it's no surprise that they've learned to adapt to the cold. A mosquito is nothing if not resilient. Based on fossil evidence, scientists say that the mosquito that we have today is virtually unchanged from what it was 46 million years ago. It means mosquitoes survived the Ice Age 2.5 million years ago unscathed.
To understand what happens to mosquitoes, you need to understand their life cycle and habits.
Mosquitoes have complex life cycles that depend on water, brought in by seasonal rainfall and human activities. Water is critical, but so is temperature. Once the cold weather arrives, their activity slows down. They fly less; they don't bite as often; they reproduce less, and their life cycle takes longer to complete.
As temperatures drop, adult mosquitoes find hiding places, such as tree hollows, animal burrows, cracks and crevices of shrubby environments, garages, basements or around our homes. These mosquitoes can only live for a few weeks in the summer but now enter diapause and can live for several months in the winter.
Where do mosquitoes go in winter, and what strategies do they have to survive the cold? It depends on the type of mosquito. There are over 3,500 species of mosquitoes, and they all have their differences. Different mosquitoes have many different ways to survive cold temperatures. Some may dehydrate to avoid freezing. Then they wait for the weather to warm up again. Others can increase glycerol levels in the body. This glycerol acts as an antifreeze to keep them warm. Some mosquitoes survive the winter on their eggs. Mosquito eggs can be incredibly resilient. They survive desiccation in hot, salty coastal wetlands during summer but also survive freezing in icy creeks in winter. Other mosquito species overwinter as adults, mate in the fall, hibernate in animal burrows, hollow logs, or basements, and overwinter in warm conditions (These are the mosquitoes that can be seen on a hot day in January or February). A limited number of mosquitoes overwinter as larvae, often buried in freshwater marshes. As temperatures rise in the spring, these mosquitoes begin to feed, complete their immature development, and eventually emerge as adults to continue breeding.
With the increasing unpredictability of weather and temperatures, it is important to be cautious of mosquito-borne diseases, even during winter. Knowing the seasonal distribution of mosquitoes helps health officials design better surveillance and control programs. This may help to understand how invasive mosquitoes survive in Pakistan's conditions, especially when there are reports that another Anopheles mosquito species has replaced the traditional malaria vector species.
Now the mosquitoes are out of sight, but they must not be out of mind. Mosquito bites are not just disturbing, mosquitoes themselves can transmit disease-causing microorganisms such as malaria parasites or the dengue virus. As it seems, mosquitoes don't really leave your garden as winter approaches. They may not bother you, but they are always waiting for the warm weather.
When the weather warms up, prepare to stop the mosquitoes!