Sometimes during a dearth the strong hives will rob the weak ones. Italians are particularly bad about this. Feeding seems to make this worse or sometimes set it off. Prevention is best. When you see that a dearth is setting in, reduce the entrances on all the hives. This will slow them all down some. But you need to have an eye on them to see that the dearth is over and open them back up during a flow.
I've noticed that queenless hives get robbed much more often than queenright hives. I had always thought it was because the robbers kill the queen, and they probably do, but when I make a nuc queenless in the fall just before I combine them with another nuc they seem to get robbed almost immediately.
One issue is being sure they are being robbed. Sometimes people mistake an afternoon orientation flight with robbing. Every warm, sunny afternoon during brood rearing you'll see young bees orienting. They will hover and fly around the hive. This is easily mistaken for robbers who also hover around a hive. But with practice you'll learn what young bees look like doing this. Young bees are fuzzy. Young bees are calm compared to robbers. Look at the entrance. Robbers are in a frenzy. Local bees might have a traffic jam at the entrance but they will still be orderly. Wrestling at the entrance is pretty much a give away, but lack of fighting at the entrance does not prove they are not being robbed, it just proves they have overcome the guard bees. One SURE way to tell if they are being robbed is to wait for dark and close the entrance. Any bees in the morning who show up trying to get in are probably robbers. Especially if there are a lot of them.
If you already have robbing occurring, here are some ways to stop it. A really weak hive can be closed up with some #8 hardware cloth for a day or two. The robbers can't get in and eventually get tired of trying. It helps if you can feed and water them. A little bit of pollen and a few drops of water will get a small nuc by. More will be required if there are more bees. After you open back up be sure to reduce the entrance. If you can feed, water and ventilate for 72 hours, you can close them up when they are full of robbers and force the robbers to join the hive. Another variety of confining them is to stop up the entrance with grass. The bees will eventually remove it, but hopefully the robbers will give up before then.
A "robber screen" can be built from scratch or from a screen door from Brushy Mt. It is a screen that covers the area around the door and has an opening in the top (you will have to make the whole affair or cut a notch in the wood of Brushy Mountain's screen door to make an entrance on the top.) This forces the robbers to turn a couple of corners to find their way in. Since they seem to go by smell this confuses them. It also stops skunks.
Vicks Vaporub around the entrance will also confuse the robbers because they can't smell the hive. It does not confuse the bees that live there.
A weak hive will sometimes get totally robbed out so there is not a drop of honey left. They will quickly starve. If you can't control the robbing it's better to combine some of the weak hives than let them get robbed out and starve. If you only have one strong and one weak, you can steal some emerging brood from the strong hive to boost the weak hive and shake off some nurse bees (the ones on the open brood) from the strong hive in the weak hive. Or you can just combine the weak with the strong. It's better than all the fighting and starving.
Michael Bush
Copyright 2006 by Michael Bush