So kids (and kids at heart), we have been getting a lot of questions about what happens to insects in the winter. Do they build little homes with elaborate hearths to keep warm? Or perhaps they take a really long nap like bears when they hibernate?
The answer is: it depends. Although we can easily say they do not build miniature houses with a wood fire to stay warm, they might use several different strategies to get through the winter.
Some insects invade houses, much to the chagrin of the human occupants. You might not notice most of these temporary residents, but a few others make themselves known. The recent invasion of the Brown Marmorated Stink Bug, Halyomorpha halys, caught the public eye when they were found to invade houses in large numbers. (Brown Marmorated Stink Bug fact sheet – PDF to download)
The exotic Multicolored Asian Lady Beetle, Harmonia axyridis (below), is also notorious for invading houses in the fall. They spend the winter months in the cracks and crevices throughout the house. They form huge aggregations where they huddle together for warmth. However, our native species of lady beetle do not invade houses. So where do they go?!
Good question! Some lady beetles migrate. The Convergent Lady Beetle, Hippodamia convergens (below), and the Two-Spotted Lady Beetle, Adalia bipunctata, are both thought to travel long distances to find suitable hibernation sites where they tend to huddle together in large numbers. That causes temperature and humidity to increase under tree bark or boulders, and that in turn helps the lady beetles survive the winter.
In addition to lady beetles, there are many other insects that also migrate. When most people think of migration in insects they think of the Monarch butterfly, Danaus plexippus. However, many other moth and butterfly species migrate south for the winter. What better way to deal with winter than to avoid it entirely?
Going back to lady beetles, they have even more strategies to survive winter. With over 450 species in North America, it is not surprising that they have developed multiple strategies to survive winter.
Many of our native species find refuge a bit closer to home. Like bears with hibernation, many insects go through diapause, a period of suspended development. Once in diapause, it takes several cues to get an insect to “wake up.” That is one of the reasons wh, on those random warm days in the middle of winter, we are not surrounded by bleary eyed insects enjoying their one day of warm weather. Diapausing insects might bury themselves deep in the soil or in the crooks of trees to avoid most of the winter weather.
Other insects have a secret weapon to survive in the brutal cold: they have a form of antifreeze in their blood! That keeps them from freezing to death during the winter. In some cases the insects keep foraging during the cold months! A good example is the Snow flea (not a flea, but actually a springtail). They have a special protein that keeps their blood from freezing in subzero temperatures. You can find them crawling around, albeit slowly, on snow in the winter. Just look for the tiny moving dark specks.
Overall, insects have many strategies for dealing with winter. I mentioned just a few of them. Insects do not disappear in the winter, you just have to know where to look to find them. Try digging in the soil or look closely at snow and you are sure to find some of those evasive little bugs.
About the Author: MaLisa Spring is an Entomology Graduate Research Fellow M.S. in Mary Gardiner’s Lab here at The Ohio State University. She is working on pollinator networks in urban environments. Find MaLisa Spring on Twitter @EntoSpring