What is robbing?
When I wrote this in July, my area’s (southeast Georgia) nectar flow has stopped and all that is available to the bees is some pollen. With foragers going out and returning empty handed, or finding nectar that is sub-par, I find that my hives get a little hot this time of year. When no nectar is available we call this a dearth which basically means there is nothing blooming that the bees will use to make honey.
So, what is a bee to do? The scouts/recruiters of the hive might come across another hive which has honey stores in it and, if the hive is weak, waltz right into the hive following the scent of honey. This foreign bee then quickly tries to get in, get the honey, and get out before being caught by the guards in the hive and removed or killed. If she can escape the hive and return home to her hive, then she will recruit other bees to where she found the honey and since honey is much more attractive than nectar or sugar water the hive can quickly be recruited to go where the original bee located the honey. In no time at all this hive with few guards is in trouble and frantically fighting off these foreign bees which we now call robber bees since they are robbing honey from one hive to bring back to their hive.
How do you know if a hive is being robbed? Signs are very evident: bees fighting at the entrance (usually spinning around on the landing board), multiple bees harassing a single bee, lots of dead bees on the ground, wax flakes on the bottom board, and wax that looks like it has been torn apart in chunks from the capping.
What can you do?
The quickest solution is to close your entrance, reduce it down to the width of a single bee. You can also block the entrance with grass and the bees will remove it over 24 hours and any robbers in the hive will either die or be forced to convert to the hive. Or you can set up a sprinkler to simulate rainfall which will wet the bees’ wings and prevent them from flying.
A robbing screen is the best answer when all else fails.
Last year I tried every single one of those methods and not a single one worked for any length of time so I chose to make my own robbing screens. There are several versions of these, one even as simple as a single piece of hardware cloth folded up, but I wanted to make the screens you see for sale at the bee supply stores for $15-$20. They look simple enough but I could not find a single plan for one on a search so I had to DIY it. I made a run to Home Depot and bought window screen and furring strips. Total cost was less than $10.
Tools you will need: staple gun, staples, measuring tape, pencil, hammer, any type of saw, jigsaw or a drill with hole saws, and nails.
I took the measurements of my bottom board from the side rails that the hive body sits on and marked that on the furring strip and cut two pieces at that length. You will need to measure yours accordingly as manufacturers have slight variations and you want a snug fit.
Once you have the bottom piece cut, cut two more pieces about 4 inches in height (my personal preference, you can make yours longer or shorter).
After that is done, take one of the longer pieces and cut or drill out a small notch in the wood. You want this to be about 3/4 -1 inch so that your bees can easily come and go. I made my entrance hole size too big, next ones I make will be smaller.
Now, nail the two short pieces to the long piece as shown. (Ignore the bottom piece over the screen for now, I did not take any pictures before that piece went on.)
Cut some window screen to size and make sure it is tight against the wood and begin to staple it down. You will need to pull the screen just a little to ensure the screen is snug to the wood.
Now attach the second long piece on top of the screen and attach it to the two short pieces with nails. The reason you have done is that it acts as a support brace at the bottom to hold the integrity of the robber screen as well as keep the screen tight.
Depending on how snug you made your cuts, you may need to use bungee cords to hold the screen in place.
As you can see in the first robber screen I made, on the right, I did not put the bottom brace and it caused the screen to cave in. The bottom brace can also be where you can correct not making the cuts snug enough. If you cut the bottom brace to where you have to jam it into the bottom board side rails then it will prevent needing to use a bungee cord.
Why does a robbing screen work?
The finished product doing what it is designed to do: prevent robbing.
Robbing screens work because robber bees are focused on one thing: the smell of honey. They want to take the quickest route into the hive to be able to rob it out and that route is through the front entrance (unless there are cracks/holes in your hive elsewhere). The robbing screen prevents this because the robbers run into the screen and frantically run around bashing into it trying to follow the scent of the honey but get blocked. The bees belonging to the hive that is being robbed however follow the pheromone scent of the hive to locate the entrance. Because of this they can actually detect the pheromone trail leading out of the front entrance and up to the top entrance hole in the robbing screen: avoiding the robbers and still being able to come and go.
Robber bees never find the pheromone trail because they don’t have the same “smell” as the hive they are robbing. To them the honey is the only thing that exists and we just made sure they can’t get to it.
If you have any questions please feel free to ask.