Ask Sam: Where Have The Bugs Been All Winter?

Mar 22, 2019

Every other Friday on Morning Edition, NHPR’s Sam Evans-Brown tracks down answers to questions about the environment and outdoors for our listeners in a segment we call “Ask Sam.” This week, producers Jimmy Gutierrez and Taylor Quimby step in while Sam is on vacation.

Sara from Suncook asks: “Where do all the bugs go in the Winter?”

The snowbanks are melting, the mercury is rising, and in some spots around New England, the peepers are already clearing their teeny little throats.  Spring triggers many changes in our environment, among them the re-emergence of our insect populations. But where have those insects all been hiding these past few months? Some have traveled great distances; others have been stowed away right under your feet.

Lauren Culler is an ecologist and researcher at Dartmouth. She studies insects, mainly mosquitoes, in cold climates: places like Greenland, Antarctica, and to some extent New Hampshire. She says the incredible thing about insects is that you can find them practically from pole to pole. That means that they’ve come up with a lot of different strategies for surviving long, harsh winters. Here are a few fascinating strategies she told us about:

Lay your eggs and die.  A lot of insects don’t “go” anywhere during the cold months, unless the insect afterlife counts as travel. Adult mosquitoes tend to have very short lifespans (males of some species live less than a week) and so they conquer the cold months by putting their energy into creating eggs that can withstand the elements. Those eggs can freeze solid or desiccate (dry out) but will remain viable until the spring thaw.

Diapause – the bug version of hibernation?   Like other organisms, some bugs have evolved to hole up and take a break during winter.  Diapause can take a number of forms and be triggered by a number of different environmental changes – sunlight, temperature, or even resource availability. Colorado potato beetles dig a few inches into the soil once crops start to wither and die. From there they overwinter until spring, when they emerge and find a good hearty meal before mating.

Migration. Insects with the right equipment can survive winter by going on a nice long vacation. Moths, butterflies, and some varieties of locusts can travel huge distances to avoid freezing to death. Monarch butterflies head to California or Central Mexico every year, though the award for most insane insect migration might go to a swarm of especially ambitious locusts that crossed the Atlantic in 1988, a non-stop journey of 4 to 6 days. That last example isn’t really weather related, but is pretty impressive nonetheless.

Anti-freeze and snowforts. Some insects are able to survive the cold months (and remain active) by building shelters or literally changing their physiology. Stoneflies are aquatic insects that live in streams and produce cryoprotectant proteins that allow them to survive water as cold as 5 degrees Fahrenheit without freezing. And should they get caught inside the ice? Lauren Culler says those same proteins “prevent their cells from being crushed by ice forming within them.”  Pretty cool superpower!  Some other insects, and also some arachnids (quick reminder that spiders aren’t technically insects), can find pockets of air between winter snowfall and ground vegetation, places where they can remain insulated and relatively comfortable until spring.

Invade your basement. Lots of insects, like the brown marmorated stinkbug, are happy to overwinter at your place. If you really want to get a sense of what a fascinating and complex ecosystem your dwelling is (and you may not) check out this intercontinental study of insect populations in people’s homes.  Here’s a tantalizing  shortlist of the biodiversity you might find in your home, as described in an article by the Washington Post

“There are prey animals, like scuttle flies, fungus gnats and book lice, which feed on sloughed-off skin and dusty detritus that collects in corners and under furniture. There are opportunistic feeders, like ants. And there are predators — cobweb spiders, ground beetles.”

All of that in your average basement. So where do the bugs go in winter? In some cases, not very far at all.