How Do Bugs Survive the Winter?
It may seem like insects are fragile creatures that can’t survive harsh weather, however, they are actually quite adaptable to varying conditions. Insects are cold blooded, which means they are unable to regulate their body temperature. Because of this, an insects body temperature will shift depending on the outdoor environment. This makes them highly sensitive to temperature change. Extreme cold or heat can affect everything from an insects flight to its cellular activity. If the temperature is too cold, insects may have difficulty moving, eating, or reproducing.
When the weather is exceptionally cold, it can be lethal for bugs. The best scenario for a bug in cold weather is if it’s also dry. While ice or snow on the ground may help form insulation for an insect, ice can be deadly. Ice crystals spreading on an insect can lead the cells to rupture, resulting in organ damage and often death. Similarly, if there is liquid water, in addition to extreme cold, it is extra challenging for bugs. They are much more likely to survive if they are dry. It is also detrimental to pests if the temperatures shift dramatically each day or if seasons change earlier than unexpected. Pests may not be prepared if winter arrives a month early.
In order to survive the winter, bugs have developed a few strategies. One method that many bugs use is migration. The Fall Armyworm living in Kentucky is an example of of this.They spend the warmer seasons in Kentucky but cannot survive the winters there. Thus, they move to warmer areas when the weather starts to get cold and only return after temperatures have become more moderate and their food is available. Another example would be the Monarch butterflies that migrate to southern California or Mexico during cold periods.
Another strategy that bugs use to survive the winter is finding shelter, by moving underground, under debris, or into buildings. One example of this would be the Southwest Corn Borers living in Kentucky. SWCB originally migrated to the central United States from warmer climates so they aren’t accustomed to cold weather. During the winter, SW Corn Borers often burrow in corn root crowns for warmth. Believe it or not, this is actually quite effective. During a period of 5 days, the outdoor air temperate was compared to the temperature inside the corn root crowns. While the air temperature outside was consistently below -2.2°F, the temperature of the corn root crowns was 17.6°F at its coldest.
Another example of insects using shelter is the Formosan subterranean termite. The termite nest is a maze of tunnels with a protective outer shell made with clay particles and termite secretions. Because of its skillful construction and the heat from millions of termites, the termite nest will maintain a consistently warm temperature during most weather.
The Subterranean Termite also uses the common insect strategy of going into diapause. Diapause is a state of arrested development that some insects enter when the days get shorter, temperatures get colder, and food sources become scarce. During this time, the insects stop feeding and purge waste. When Subterranean Termites enter this state, they stop foraging for food and simply huddle together for warmth in their nest.
Many bugs have also evolved to have impressive defenses against ice. In fact, some bugs are actually freeze tolerant. This means that they can combat ice formation on their body by producing ice nucleating proteins that control the ice. The majority of insects aren’t freeze tolerant but are instead freeze avoidant. Prior to the cold weather, freeze avoidant bugs acquire a special combination of carbohydrates that act like antifreeze. The antifreeze is quite effective at preventing ice build up on their bodies as long as it is not a sudden freeze or temperatures aren’t too extreme.
While cold temperatures can be a challenge for insects, they are actually more prepared than you might think. Whether it’s migrating south, seeking shelter, entering diapause, or evolving to fight ice, bugs have adapted to fight the cold.