Ask Blue_Nose

Another interesting question comes to AskBN:

"Where do all the creepy crawlies go when winter comes? You see more inside the house, but where do most end up?"

As the September days are bringing cooler temperatures, this is one question our arthropod friends will be asking themselves. As luck would have it, entomology is one area in which I'm particularly an expert.

We can discuss the general methods bugs use, and we'll also look at the specific examples of some that we're most familiar with here in Canada. There are almost as many survival methods as there are varieties of crawling-thing, so there's no chance that I'm going to touch them all. I'll try to summarize them, though, and we'll basically break it down into cold-avoidance and cold-tolerance. Different species use either one of these measures, or a combination of both.

There are several methods of avoidance. The most apparent method is migration, for which we have the example of the Monarch Butterfly - Insects simply move to areas of warmer climate. Many beetles survive the winter as adults by finding a sheltered area (such as beneath logs, leaves, etc) that aren't exposed to the harsh environment to hibernate. It's not so much the cold that is bad for them, as it is the repetitive variation of conditions (freezing and thawing). As you mentioned, houses and other structures are excellent locations to provide this security, and many lie dormant in the nooks and crannies of your house (such as underneath the siding of your house), without ever walking around inside where you'll notice them. Ladybugs (lady beetles, ladybirds, or whatever you wish to call them) hibernate as adults in this manner. Ants will close off the entrance to the nest, become mostly inactive (so-called 'restless hibernation'), and simply survive on excess food on which they gorged during the autumn.

Some other methods of are similar, except the insects overwinter in the larva or egg stage. Eggs are laid under bark, in plant stems, under the snow (which provides a significant amount of insulation to the underlying soil) or in the soil itself, where they are protected from the weather and predators (this is the method used by grasshoppers, for example). Overwintering in the larval/pupal stage is also common for most plant eating caterpillars - the cocoon provides them with protection from the weather. Bodies of water which don't completely freeze are often excellent places for insects to hibernate in the winter (dragonfly nymphs use this method). Various spiders can overwinter as eggs, immature spiders, or adult spiders, under bark, in the soil, or in egg sacs.

Honey bees actually heat their hive during the winter - workers feed on stored honey, and convert the energy to heat, and the hive remains at a highly regulated temperature of about 7°C throughout the winter, and an impressive 34°C in the nursery, where the baby bees are kept.

Some insects reduce the chance of freezing by dehydrating themselves - less water means less freezing. Others produce antifreezing proteins ("Cryoprotectants" - cool word of the day, pun intended) which lower the freezing temperature of their bodies (supercooling in this manner has been observed at temperatures as low as -60°C in the arctic). An example of an insect using this method is the snowflea, which can often be seen crawling around in the snow.

Even with these freeze-avoidance measures, it's often not enough, and freeze-tolerance measures are required. Insects in the arctic must be able to tolerate sub-zero temperatures for extended periods, so avoidance will not always work.

Some insects have just become tolerant of freezing at moderate temperatures, and simply resume living when they thaw out. Others produce what are called "ice nucleating agents", which are extracellular fluids that encourage the ice to begin forming outside the cells instead of inside, where they'd do more damage.

Well, that's a heck of a lot of information (hopefully not too dry for you), so I'll leave the explanation at that. The interesting thing about it is the variety of methods, which reflect how the species live during the rest of the season.

To finish things off, a little anecdote: One day back in my highschool days, while walking down the street at lunch, I noticed a little honeybee sitting on the sidewalk. As it was a cold day and she appeared to be quite frozen, I picked her up as a keepsake. I walked down the street with her in my cupped hands, and just as I walked into Subway, I felt a buzzing in my hands. Surprised, I threw the bee into the air, realizing that it was, in fact, still quite alive. It's extended life was not to last, though, as it managed to sting the hand that saved it before escaping - So it goes.

Thanks for the question, and hopefully I've provided you with a suitable answer, As always, if you have more questions, you know where to ask.