HOW BUGS RIDE OUT THE WINTER – TUESDAY, FEBRUARY 13, STEVE CLARK – 88.9 WCVE producer Steve Clark and entomologist Dr. Art Evans discuss how some insects are adapted for surviving cold winter temperatures.
SC: I’m Steve Clark with Dr. Art Evans, entomologist, and this is What’s Bugging You. Maybe you can tell from my voice that winter has set in.
AE: (laughing) You do sound a bit thick today.
SC: Oh well, it’s here until spring. I’m hoping for an early thaw.
AE: I’m sorry.
SC: What happens with the bug populations? I mean we’ve got all these grubs under the ground, all the little triungulins running around, and all the ground-nesting bees and queens, and the yellow-jacket queens . . .
AE: Right, right.
SC: Are most of these going to survive this bitter winter?
AE: That’s a popular query. You know a lot of people have approached me online and elsewhere, “What happens to all the insects in this really cold weather?” And more importantly, a lot of people who aren’t big fans of insects or are at least are looking forward to fewer pests are wondering, “Are there going to be fewer of them in the spring?” And the short answer is, “No.” (laughing) The insects that are already here are adapted for this kind of weather. Back in fall many of them had already begun the process or even completed the process of secreting themselves beneath bark, deep in the soil, under rocks, in different places where they are protected from frost. Because whatever water is in their bodies turns to ice, and those ice crystals become razor sharp and will slice up tissues and just turn them into mush on the inside. So it behooves them to seek shelter, and instinctively that’s exactly what they do.
SC: Well, aren’t there some that have like an antifreeze?
AE: There are some insects that have chemical compounds in their bodies that function as antifreeze that lowers the freezing temperature of the moisture that’s in their bodies so it doesn’t freeze. And there are other insects that go through a physiological process where they actually shunt water out of their selves, so when it does freeze, the crystals form outside the cells and don’t damage them.
SC: How do mosquitoes overwinter?
AE: Overwintering depends on the mosquito and where they are, but mosquitoes overwinter as eggs normally.
SC: Oh, okay. Because I was just thinking about the cold weather and why if it really had an impact why Alaska and Maine have these black fly and mosquito abundances.
AE: Well, first of all they’re adapted to those temperatures, and they overwinter in a stage that’s best adapted to surviving low temperatures. Insects undergo a process called metamorphosis. Some of them go through the egg stage, larvae, pupae, and adult. Others go through a nymphal stage and then go right straight to the adult. Those different stages have different adaptations. Some of those stages are better adapted for surviving colder temperatures than others. So you’ll find different species surviving winter during the egg stage. Others will do it through the larval stage. Others are best suited to ride out the cold winter as adults. The number of insects in the following season was decided in the previous season by the number of eggs that are laid. But rest assured that the insects that are native to this region and some of the ones that were introduced a while back are all adapted for this kind of weather, and so I’m sure they’ll ride out the cold just fine.
SC: There might be minor variances over the years, but largely they’re still going to be here.
AE: That’s right, lucky us!
SC: (laughing) Dr. Art Evans is the author of Beetles of Eastern North America. You’ll find photos, audio, and a link to Art’s Facebook page at ideastations.org/radio/bugs.
Photo: Some insects, such as the red flat bark beetle, Cucujus flavipes, beat the cold by producing chemical compounds that lower the freezing point of their tissues, enabling them to survive prolonged subfreezing temperatures.