Hello pollinator enthusiasts! It's been a little while since I've written to you, and I apologize for the long delay, but a few times over the past couple weeks, I've had similar questions from a number of sources, and I thought it was time to address it. Right now in the northern hemisphere, we are in the middle of winter. From where I am in Pullman, that means cold, rain, snow, wind, ice, and sleet. In other parts of the world, winter means consistently freezing temperatures and snow for months, while in other areas (ahem, California), winter means you might need a light sweater a few days of the week. Right now, in the winter of 2016, we're experiencing the El Nino weather phenomenon which means that western Washington, Oregon, and most of California are receiving more rain than usual. This brings me back to the topic for this entry: why don't bees fly in the rain? There are a lot of answers to that question, depending on the season. Most wild bees (such as sweat bees, leaf cutter bees, other ground nesting bees) go dormant or die at the end of the fall season, and then the eggs from the previous year hatch in the spring and emerge a bit later, in late spring when we start seeing them.
But what about during spring and summer rains, when bees would otherwise be flying? Well, again, there are a few reasons why bees are "fair weather fliers." First, imagine the size of a raindrop in comparison with your own body: one raindrop barely makes your notice because they are so tiny, right? But now think of that in comparison with the size of a bee: a medium sized raindrop might be 1/4 the size of a bee's body. That would be like dumping a 5 gallon bucket of water on your head every time you got hit with a drop. Those drops are going to seriously alter a bee's course of flight, make it very difficult for them to see (like driving through thick fog or rain), and be generally unpleasant. Second, bee bodies aren't constructed to be wet. While humans have skin that makes us relatively waterproof and keeps our internal organs from getting soaked, insects have their exoskeleton on the outside. If the cuticle (another word for the outermost part of the exoskeleton) were completely sealed, the insects would be quite waterproof. However, if that were the case, they also wouldn't be able to move. The joints in insect bodies allow for movement in the same way our knees and elbows bend- the difference is that because insect joints are "open" or without a protective layer like skin, this allows water to penetrate their body. In 1945, an insect ecologist name Thompson wrote about this unfortunate fate:
"A man coming wet from his bath carries a few ounces of water, and is perhaps one percent heavier than before; but a wet fly weighs twice as much as a dry one, and becomes a helpless thing."
Although bee bodies have some major differences from flies, in this sense, they are relatively similar. Most people don't prefer to go out in the rain if we can help it, because we get a little wet and that makes us feel a little cold. But if you were a bee, a rain shower would feel more like this: you're flying around and suddenly a bucket of water gets dropped on you. You're definitely not wearing a raincoat, and instead of getting drenched, your body acts like a vessel and you suddenly weigh twice as much as before. This makes it impossible to fly, so you're stuck out in the muck and the rain until the rain stops long enough for you to dry out and fly home. If you live in western Washington, that rain might not stop for 6 months. If I were a bee, I wouldn't go out in the rain either!