Dead bees in winter: what is normal?
Many new beekeepers are concerned about dead bees in winter, especially the ones that accumulate on or near the hive entrance. Every week I receive several questions about this, so I want to elaborate.
Even in the healthiest of colonies, bees die every single day. According to Bees of the World (O’Toole and Raw) a normal-sized colony loses about a thousand bees per day in the summer. These losses are replaced by a busy queen that may lay upwards of 1500 eggs per day. Most of the summer losses are foragers that die on the job and we never even notice them. Since they are out of sight and out of mind, most beekeepers aren’t too concerned about these daily losses.
Bees dies in winter, too
But bees continue to die every day even in winter. The losses are not as high because the bees are not foraging and because winter bees have special adaptations that allow them to live longer than summer bees. Still, many die every day, and they die at home where we can see them lying on the landing board or peppering the snow.
If you consider that your healthy colony may have 50,000 or maybe even 60,000 members going into the fall but may have only 20,000 come spring (WSU Extension) somewhere along the line you lost 30,000 to 40,000 bees. That’s a bunch.
For the sake of argument, I’ll take the smaller number of 30,000 and divide it by 182, which is the number of days in October, November, December, January, February, and March. That gives me 164 bee deaths per day. The larger number of 40,000 gives me 220 bee deaths per day.
Hauling out the dead is normal
Of course these numbers are approximations. But most people who write to me are concerned about “five or six dead bees” on the landing board or “two dozen dead bees on the snow.” As you can see, those numbers are just natural attrition and are nothing to worry about.
For years now my own hives have been within a short walk of my house. Nearly every day I walk up there (for my benefit more than theirs) and I flick the dead bees off the landing boards. What I’ve noticed is that a new pile of bees every day is a signal that all is well inside. Only a healthy colony has the manpower—er, beepower—to dispatch undertaker bees to clean up the bodies. On warmer days they fly them off and drop them on the ground, but on colder days they just shove them out the entrance. In either case, all is well.
Now I begin to get concerned when I see no bodies, because then I wonder if the colony is as strong as it should be. In fact, in several instances this was my first clue of a failing colony. It’s not a sure thing, but it is a piece of information you can use when making management decisions or when you are trying to decide if you should peek inside.
Look before you flick
But don’t forget to look before you flick. A couple of years ago, I found the queen among the five or six dead bees at the entrance. I was able to combine that queenless hive with a nuc in the middle of winter, and I ended up with a vibrant, healthy colony by spring.