By Kaitlin McHenry
Ever wonder what the insects are doing in the cold winter months? Michigan is capable of some harsh winter conditions. Although every winter is slightly different, it is safe to say you will not see bugs frolicking in the meadows for several months of the year. But every spring, they return in countless numbers. So, how do these tiny fragile creatures survive?
Some bugs migrate to warmer regions like birds do, and those that stay have plenty of tricks. The bugs who tough out the winter will either survive as full adults, or they will use the winter for development in earlier growth phases.
It’s not always obvious which bugs migrate. Some species like the Japanese beetle seem like they migrate because they show up in swarms mid-summer, but actually that’s when they finally mature and crawl out of the soil that they’ve been hanging out in as grubs all winter and spring.
Insects have different lifespans ranging from hours to days to years, and sometimes one species has different lifespans for different individual roles (queen bee vs the worker drones). Their projected lifespan / life cycle makes a difference in how they survive winter because no matter what, those insects must be strong enough, protected enough, and live long enough to outlast the winter season. So, if an adult of a certain species of bug only lives a few hours, it must hide in a different form over winter such as an egg. Bugs that overwinter in an earlier phase of growth include eggs, larvae, nymphs, and pupae (Smithsonian Institution).
Larvae (larva) are the grub form of an insect. These are actively feeding and growing, but they do not resemble their adult form (Neuman 2023). These larvae find shelter in leaves, and some are capable of digging themselves into the soil. The deeper they go, the more protected they are. Some have a special ability to preserve themselves from freezing with a body component called glycerol (Smithsonian Institution).
Nymphs are miniature forms of the adult insect (Neuman 2023), and many of them remain active over the winter in ponds, lakes, and rivers! These include dragonflies and mayflies (Smithsonian Institution).
Hibernating pupae are an inactive form of development when the insect is cocooned and in a transition state (Neuman 2023). While monarch butterflies are migratory and have pupae (chrysalis) in warm conditions, some moths will hibernate through winter in the pupal stage (Smithsonian Institution).
The insects which brave the winter in their adult form have many unique methods too. They use some of the methods already mentioned such as finding shelter in leaves, hollow trees, burrowing in the ground, and creating an “antifreeze” in the bodies with glycerol. Some of them remain semi-active, and others enter a state of hibernation (Smithsonian Institution).
Every insect species is unique, and every winter is different, but they have their ways to make it through year after year. Winter conditions can affect their survival rate. Colder winters are said to reduce their populations, but in reality, inconsistent conditions have more of an influence. Similar to the lavender plants, snow provides additional insulation which protects bugs against harsher conditions. Snow also helps keep the ground at a more consistent temperature.
Works Cited
Neuman, A. (2023, July 27). Life stages of insects • UAV-IQ. UAV – IQ. https://www.uaviq.com/en/2023/07/life-stages-of-insects/
Raupp, M. J. (2014, December 8). Surviving winter, part III: Egg cases of the praying mantis, mantis religiosa , Chinese mantis, Tenodera sinensis , and Carolina Mantis, stagmomantis Carolina. Bug of the Week. https://bugoftheweek.com/blog/2014/12/2/surviving-winter-part-iii-egg-cases-of-the-praying-mantis-imantis-religiosai-chinese-mantis-itenodera-sinensisi-and-carolina-mantis-istagmomantis-carolinai
Smithsonian Institution. (n.d.). Where do insects go in the winter? | smithsonian institution. Smithsonian. https://www.si.edu/spotlight/buginfo/winter