You walk into your bathroom one afternoon and hear an unfamiliar buzzing noise. Is it the fluorescent lighting fixture? Is there a fly in the room? No! There’s a honey bee trying to get out of the bathroom window. And there are two more honey bees crawling up near the bathroom ventilation fan. You decide you don’t really have to use the bathroom at the moment and walk to the kitchen, and as you look out the window you see yet another bee slowly flying up and down, staring at the windowsill, and investigating any little nooks and crannies that it finds.

What’s going on?!

What are swarm scouts?

When a swarm of bees leaves their original hive with their queen, they settle on a branch or other temporary resting place while the swarm’s scout bees search for a new home. The scouts are older bees – highly experienced foragers – who are already strong flyers and are familiar with the area for two or more miles around the original hive.

As the majority of the swarm sits and waits, the scouts (about 300-500 bees) fly and search for knotholes, cracks, crevices, and cavities to investigate. If they manage to find a potential nest site they will take time to evaluate it, examining its entrance and interior, before they return to the surface of the swarm. Once they get back, the scouts report their findings using the dance language of honey bees.

The discovery of dancing scout bees

The first person to figure out what swarm scouts were really up to was a German scientist named Martin Lindauer. Lindauer was studying bees in the heart of Munich soon after the end of World War II. As he watched the bees on the surface of a swarm, he saw that some of them were performing waggle dances. The dance language of honey bees had just recently been decoded, and Lindauer watched as notably “dirty” bees danced over and over again.

Why did he call these bees “dirty”? Because as they searched for nesting cavities in bomb-damaged Munich, the scouts became covered in white dust (plaster), black dust (soot), and red dust (damaged bricks). Lindauer realized that they weren’t dancing to advertise nearby flowers, but instead they were poking around the damaged buildings nearby and then reporting promising new homes to each other. Almost as soon as the dances began to point in the same direction, the entire swarm would take off, and Lindauer would have to chase the cloud of bees through the streets of Munich to confirm that the swarm flew to the location advertised by the most popular dance!

What are scout bees looking for?

Professor Tom Seeley, now retired from Cornell University, has spent much of his career studying how swarms select new nest locations. By giving the bees different possible nest locations and then “asking” swarms to choose between them, he was able to identify many of the key features that swarm scouts use to choose between their options.

Swarms prefer a site with a small entrance (under about 20 square centimeters) facing to the south and located at least 5 meters above the ground. They also prefer a relatively spacious cavity of at least 30-50 liters. (Note: A 10 frame deep hive body has a volume of about 42 liters.)

Swarms strongly prefer a cavity that already contains beeswax combs inside, probably for two reasons: First, combs are costly for bees to produce, so pre-built combs save the new colony time and building resources. Second, if scouts discover a cavity full of beeswax, it suggests that another honey bee colony had previously lived in the cavity successfully. (Although – Why did the previous bees who lived there die?)

In addition to his many scientific publications, Professor Seeley also co-authored a free booklet published by Cornell called “Bait Hives for Honey Bees” that describes how to offer swarm scouts the “ideal” new nest location and to attract nearby swarms.

Professor Seeley’s research revealed something even more amazing about swarm scout behavior. By watching (and videotaping) scouts dancing on the surface of swarms, he was able to watch as the scouts danced to advertise many possible nest locations, and then slowly reached a consensus on the best of the options that their scouting efforts had discovered. Using a strict set of “voting” rules, scout bees share their personal information about different nest sites and allow the swarm to collectively choose their new home. He summarized what he learned about how swarms vote on nest sites in his acclaimed and fascinating book, Honeybee Democracy.

So what should you do about the bees in your bathroom?

Will the scout bees ever leave your bathroom alone? Well, they might. As long as your vents, walls, chimneys, and other cavities are small or otherwise unsuitable for nesting, it’s unlikely that the nearby swarm will move in. They’ll find a better location, and you’ll just have to clean up a few poor scout bees that got lost or trapped while they were house hunting. The swarm will usually choose and move into their new home within about three days, and the influx of inquisitive scout bees around your house should immediately end.

You might consider temporarily plugging up holes in your siding, or taping a piece of plastic over your fan’s exhaust vent, just to make your home a less appealing place to the scouts. As long as you’re only blocking scout bees for a few days, that should work quite well. Don’t try to seal an entire colony of bees into your wall after they’ve already moved in though – they’ll either find their way into your house in an attempt to escape, or they’ll die in the wall and begin to rot (and smell).

If a swarm DOES decide to move into your house, you need to get them out or find someone who can get them out for you. You can check out Betterbee’s Swarm Catcher list for beekeepers near you who perform “cut-outs” to remove unwanted bee colonies from walls and other structures. (If you’re a beekeeper who performs cut-outs or collects swarms, contact us to get your name added to our list!)

So what should you do if your home is suddenly surrounded by curious scout bees, poking around holes in your siding and flying down your chimney? Instead of panicking or reaching for your spray can of insecticide, perhaps you should just enjoy the marvelous process of honey bee decision-making. (But it probably wouldn’t hurt to close the damper on your chimney and stuff something into those siding holes to reduce the chance that you’ll wind up with 12,000 new housemates in the next day or two!)