How do bugs survive Canada's harsh winters?
Don’t forget that under all that snow, there’s a whole community of insects, spiders, and other arthropods waiting for the spring as much as you are.
Curling up to a nice warm fire when you’re wrapped in a blanket on a cold, wet fall day is one of the best feelings, but we’re not the only ones that enjoy being all wrapped up against the cold: There’s a bunch of arthropods that love curling up beside you and others that want to be asleep under a bed of leaves.
Bugs and spiders need to survive the winter as well as we do, but they’ve got a variety of strategies to ensure their continuation that don’t usually involve a furnace and a warm blanket.
I recently noticed that my basement seemed to suddenly be an epicentre for a spider party – so many of those long-legged ones that create fuzzy webs that seem to appear out of nowhere. This seemed unusual and somewhat alarming, but I wasn’t sure if this was a normal thing, or if I’d somehow created some sort of bug and spider paradise.
I suspected that there might be an association between the cold weather and the influx of bugs and spiders into my place. To find out, I headed over to the University of Guelph Arboretum to talk to Chris Earley, Adjunct Professor and Interpretive Biologist at the University of Guelph Arboretum.
Why are insects heading inside?
My first question was, what the heck do insects in the winter do other than try to set up homes in my basement.
He laughed and answered, “Insects are exothermic, also called cold-blooded blooded and when it gets cold out, they suddenly can’t function. Really, they’re just trying not to freeze. One way they do that is to migrate; think monarch butterflies or the Common Green Darners. They fly south and avoid the cold.”
“Others that stay here need some sort of freeze tolerance. So, insects try to reduce the chances that the water in their bodies don’t freeze and create sharp crystals that will burst their cells. That can be done in a few ways; reduce the amount of water in them or use some sort of antifreeze. They’re not eating, barely breathing, and really not doing much of anything, and that will allow them to make it through the winter.”
This appeals to the lazy side of me, but I do have winter storms to chase.
“Some insects are going to overwinter as an egg or a caterpillar or pupa, or an adult. For example, the woolly bear caterpillar overwinters as well, a caterpillar in the leaf litter on the forest floor. Some will overwinter under bark; some will even be exposed on the ends of branches. Little tiny caterpillars that can be completely exposed, but because they have this antifreeze, they’ll survive the winter.”
“Some are aquatic, so things like dragonflies or damselflies, their nymphs (kind of like larvae, but a bit different) are active all winter, moving around at the bottom of ponds, feeding and growing so that at the beginning of spring, they’re able to emerge from the water and start flying around.”
Of course, the best place for insects to overwinter might be the same place we do it – inside a nice warm home. However, for many insects and spiders, it’s not that simple and, in fact, many species need the cold to survive.
“If species head inside to keep warm, there’s the danger that they may run out of energy or moisture before the outside warms up again. A lot of insect species don’t want to be inside because they’re adapted to living outside.”
Do insects like being inside people's homes?
Our homes aren’t particularly good habitats for many species and thus, not good hunting grounds for predator species even if they want to stay warm.
It’s a big part of the reason our homes aren’t immediately stuffed full of bugs every time the temperature drops.
There are some species that do like to make our homes their home, and so Chris and I went inside the Arboretum main building to see if we could find some of them. It took about 25 seconds for Chris to find one of the more ubiquitous species seen at this time of the year, a ladybird beetle.
I crowded in close to Chris as he pointed out one of the beetles hiding on the frame of a large window.
“Over here, we have an Asian Multicoloured Ladybird Beetle, and they really like to get in corners. They’re often found in groups, but this one is a little lonely. They’ll usually start the winter with larger groups, but as time goes by, individuals might move to a different area, or some will die off. Some people get upset about having insects in the home over the winter, but really, they’re harmless, don’t take up much room, and just after a warm place to hang out until the spring. In the spring, they’re like, ‘I’m outta here, I don’t want to hang around, I’ve got a life to lead outside. So they don’t stay inside and head out as soon as they can.”
I asked Chris if some species take up a more permanent residence in our homes.
“Some species are adapted to living with humans. Cellar spiders are a good example – you have them, I have them, everyone has them. They’re an introduced species, and they’re helping keep your house pest-free.”
Turning on the furnace, getting a cup of hot chocolate, and watching the snow fall outside is always an awesome feeling, but don’t forget that under all that snow, there’s a whole community of insects, spiders, and other arthropods waiting for the spring as much as you are.
Helping insects ride out the winter
You can help them out by leaving leaf litter in your garden, not cleaning up plant debris in those same gardens and not worrying about those insects and spiders that make your home their own.
Our local arthropod community will thank you!
Header image: file photo via Unsplash.