Yesterday was the hottest and most humid day of the summer, and the bees were feeling it big time.

Bees bearding after a hot humid night. (August 30, 2011.)

That’s the bees in one of my hives bearding outside the hive. (The Star Trek symbol is used as a distinctive homing marker for the bees. It probably doesn’t make any difference to them, but too bad.) The photo was taken around 7:30am this morning. They were bearding twice as much last night. It was about 30°C (86°F) when I went to bed around 10:30pm.

From what Rusty Burlew tells me, bearding is a behaviour that’s triggered by excessive heat or humidity, which is made worse by over-crowding and a lack of ventilation inside the hive. The bees leave the hive because it’s cooler outside. You can read more about bearding at Honey Bee Suite.

The hive already has a screened inner cover and a ventilation rim to help with ventilation, but it looks like it could use a screened bottom board too. I’m building one today and hope to have it installed soon. My foundationless hive has a screened bottom board and it looked like this at the same time Hive #1 was bearding this morning.

Bees with a screened bottom board not bearding so much after a hot humid night. (August 30, 2011.)

March 2019 Postscript: For the casual joe just poking around the internet for neat looking beekeeping photos, the ones in this post might not seem like much, but as a guy who’s been experimenting with beehives for almost ten years now, I’m intrigued by my early-beekeeping powers of observation, especially when they uncover things like this. I haven’t messed around with screened bottom boards for two or three years now. My homemade ones were left outside one winter and rotted into mush and I haven’t used them since. But now I’m wondering if I should try them again. The photos in this post and others I’ve uploaded show a significant difference between hives that have screened bottom boards and ones that don’t. I’m thinking I might get a small mirror that I can place in front of a bottom hive entrance and if the mirror fogs up, then it might be a sign that the hive could use a screened bottom board, or least some extra ventilation of some sort. Interesting.