Where Do Insects Go in the Winter?
Where do insects go in the winter and why should we care? We must care because many insects are pollinators. Without pollinators, our existence is in peril. Why? Because much of the food we consume comes from pollinated plants! Without pollinators, we starve! Got your attention? Read on to learn more.
Insects have many options during the winter months, but none of them involve wearing warm coats, long socks while sitting by a fire drinking hot chocolate. Their winter life is very different.
Depending on what type of insect you are and what life cycle you partake in, you may migrate, enter diapause, overwinter as nymphs, larvae, pupae or eggs.
Some humans are winter migrators. On the east coast, think of the snowbirds entering Florida in the winter! But none can compete with the Monarch Butterfly and its travels each winter to the oyamel fir forest in the Sierra Madre mountains of Mexico. When spring arrives, a future generation of the monarch makes its way back north to spend the warmer months. What a glorious trip!
To better understand what other insects do during the winter, let’s refresh our memory of insect life cycles. Insects have either a three-stage or four-stage life cycle. The three-stage life cycle is called incomplete or gradual metamorphosis and insects transform from egg to nymph to adult. The four-stage life cycle is called complete metamorphosis where insects transform from egg to larva to pupa to adult.
Many insects overwinter in one stage of their life cycle. Praying mantises overwinter as eggs. In the fall, adult females lay egg clusters on small branches which are protected for the winter inside papery cases known as ootheca. Nymphs will hatch in the spring. If you are a moth in the silkworm family, you overwinter as a pupa in a cocoon hanging from a tree limb. Luna moth pupae survive in a cocoon in the leaf litter on the ground. If you are a woolly worm (woollybear caterpillar), you overwinter as larva secure in leaf litter waiting for spring.
Some insects have an amazing super power allowing them to replace the water in their bodies with glycerol, which prevents them from freezing. It’s called a cryoprotectant and acts like antifreeze in your car! That vodka bottle in your freezer? Same concept. Others protect themselves from freezing by burrowing deep into the soil to stay below the frost line. These strategies are known as freeze avoidance.
Some insects have other ways to survive typical winter weather. According to Michigan State University, “death by freezing isn’t so much related to low temperature itself as it is the result of ice crystals forming in the body. Rapid formation and expansion of ice crystals cause cells to burst, resulting in organ and gut damage. Some insects are freeze-tolerant—they actually survive the formation of ice crystals in their body by producing ice nucleating proteins that “control” the freezing process.” Wow!
No matter which overwintering strategy is employed, all insects will eventually die if it gets cold enough.
For insects in the three-stage life cycle category, they may overwinter as nymphs. Many dragonflies and mayflies spend the winter as nymphs feeding and growing in ponds, lakes and streams, sometimes under the ice!
So what happens to the insects when we have these roller coaster temps—cold one day, hot the next? It wreaks havoc on them! Climate change affects all flora and fauna, including small insects.
Some insects have their own form of hibernation called diapause. These insects seek shelter under tree bark, under rocks or burrowing underground. Who’d have ever considered the sleepy bugs underneath our feet as we take our winter hikes!
Smithsonian magazine reminds us, “diapause is an adaptation to survive the winter. Insects’ growth, development, and activities are suspended temporarily yet the insects’ metabolic rate is high enough to keep them alive. Temperature is not the main factor that triggers diapause. The shorter days that lead-up to winter help signal the insects it's time to get ready for dormancy. Climate change can cause the warmer days to last later into the fall creating confusion in insects. Mistakenly thinking it's spring or summer, they often end up aborting the diapause process to begin looking for food or mates leaving them unprepared when winter actually strikes.”
Some butterflies stay in Tennessee for the winter entering diapause as adults. The mourning cloak, Question Mark and Eastern Comma all spend their southeastern winters hiding under tree bark, hollow logs and trees, between cracks and crevices in buildings. These micro-habitats become their winter home providing safety and shelter.
So once again, why do we care what happens to insects in the winter? According to USDA, “Honey bees and other pollinators are critically important to securing the nation’s food supply and providing ecosystem services that insure plant diversity, soil stability, and species richness. Fruit and seed yields increase when many bee species are present, whether in undisturbed ecosystems or in crops such as apples or almonds, where pollination by both honey bees and native bees generates greater yields and higher quality fruit.”
If you like living …stop the leaf blowers! Stop the trucks that take our leaves away to be mulched. Leave the leaves, create twig piles, leave decaying logs in place-these are all critical habitats for the life saving insects.
