During winter, most insects will die as a result of the cold or they try to protect themselves from the cold by choosing a suitable place for shelter. Their own biological cycle can ensure the existence of some transitional generations, adapted to the cold and survival in extreme climatic conditions. However, this should not make us believe that these animals are defenseless in the face of snow or cold and that most of them will die, as some myths tell, including “The Cicada and the Ant” by Aesop.
Insects actually have various weapons at their disposal to survive the extreme climatic conditions of winter, but evolution has led them to conserve resources and energy, basing most of their reproductive success on the favorable environmental conditions of spring and late summer. After this adaptation, most species seem to disappear during the dark months of the end and beginning of the year, when in fact their representatives, or they have hidden in some niche or lie in the form of eggs, pupae and resistant stages in different types of different environments.
This process is obviously most exposed to insects that inhabit mainly areas of the planet with a continental climate, but also in the Mediterranean and desert regions there are species that breed in the winter months and have a different metabolism. Among them are several examples of insects that hibernate, that is, they lower their metabolic rate enough to enter a type of quiescence scientifically known as diapause. A classic example of these species is the European ash cicada (cicada orni)so dear to Aesop, who does not actually die in winter.
Why do insects disappear in winter?
As we have seen, insects are not exactly defenseless when faced with the cold. They just their number is decreasingversus summer and try to escape the grip of winter by finding a shelter to spend the hardest months of the year.
For example, cicadas and ladybugs take refuge in some niches in the ground and in trees to surround themselves with plant material in a sufficiently warm environment, while outside rain and especially snow transform the landscape beyond recognition.
Some species, such as aphids, choose to produce instead autumn generation designed exclusively to face the arrival of cold. They are the only ones that reproduce sexually during the yearproducing an egg that turns out to be lo the hardiness state of the species during the winter. Sexual females actually lay their eggs under leaves or in some mounds of vegetation to protect the future generations, which will reproduce exclusively in the spring parthenogenetic deposition.
What happens to insects in winter?
survive the winter different species decide to gather and form colonies, and they hope that together they will face not only the cold, but also the lack of food. Among other things, it also seems to be the stimulus that led some species – such as bees and ants – to develop their social structures during certain very cold periods on Earth. It actually allows you to all live together in a colony during the winter save a significant amount of useful energy to maintain body temperature and allows these organisms to defend themselves against potential attacks by winter predators.
In some situations, insects may even enter diapause, which will lower their metabolic level enough to appear dead. Some species can stay in this state for several years until their body gets warm enough or they feel ready to start looking for a mate.
Often, when an intense drop in temperature affects insects, it is possible for them to even allow themselves to be covered with ice without suffering damage. The secret of this survival mechanism is linked to certain genes that allow these animals to resist freezing through the production of certain antifreeze enzymes in their cells. Freezing could actually destroy the cells in their bodyin response to the formation of water crystals in their cytoplasm. However, with these enzymes, the water in the cytoplasm and other body fluids does not freeze, and only the insect’s outer exoskeleton remains in contact with the ice.
Other groups of insects, such as Lepidoptera, may also choose to form cocoons in late autumn to protect themselves from the climate at the same time as the development period. This option has a two-fold advantage. It allows these insects to escape the cold but also to grow in anticipation of metamorphosis and spring breeding.
Where do insects hide?
Many insects are already hiding in autumn inside dead trunks or in bark cracks living trees. Some species prefer to dig a small hole in the ground instead or seek shelter under dry leaves and plant debris. The decomposition of this material indirectly releases some heat and allows the insects to find some food sources, especially if they are detrivorous species.
Ants and bees find shelter instead within their colonies and at most they may decide to move in the fall in search of better territory. Flies, on the other hand, choose to look for some mushrooms or dead animal carcasses to lay their eggs and allow future generations to immediately find resources as soon as they are born.
Aquatic species that they are in danger of freezingwith the formation of ice sheets on the surface of lakes, they instead choose to either move deeper or take refuge in the moist sediments on the shores of water bodies. This way they stay safe, away from layers of water that freeze.
Some specific insect species may also choose to seek refuge inside the caveswhere temperatures remain controlled and above 0 degrees Celsius throughout the year.
Where are they hiding in the house?
In the absence of natural shelters, insects may decide to do so occupy our buildings, especially if they are abandoned and in direct contact with natural ecosystems. Insects find refuge in particular in attics and cellars, especially if the building materials used are those that he appreciates the most, such as wood. Sometimes they even find refuge in mailboxes, as has happened several times in the United States, or in wood piles prepared for the winter.
Insects enter our homes primarily through open windows and doors, but also through cracks in walls or chimney caps. However, their natural predators may be waiting for them there, such as mammals and spiders waiting for a snack.
In an attempt to escape bad weather, some social insects can settle in homes. Just think of the high number of bees, wasps and hornets that become infected every year roller shutter boxes or abandoned floors of buildings.