This summer, I captured a small swarm in one of my swarm traps. My swarm traps are really extra deep 6 frame nucs, so I can leave bees in them for a while if that seems like the thing to do.
This colony was maybe 500 or 1000 bees, so I just left the trap in the tree for a couple of weeks before I investigated it. When I looked, I discovered the colony had a marked queen - one of my own queens, distinguishable because I didn't have any red marking paint, so she had a dab of orange-red fluorescent paint. I decided to keep the colony going, as I thought the queen might come in handy if I needed one. I gave them a frame of honey and let them alone.
Everything was ok, until there was a sudden dearth. Before I realized it, the trap had been robbed of all its honey. The robbers were gone, and the bees were repairing the combs.
So I gave the colony another frame of honey with some bee bread, and sealed up the box to prevent robbing. Then I moved it to a new location, and installed a robbing screen, with an entrance 10 inches or so above the hive entrance. Everything looked OK, so I reopened the lower entrance, restricting it to about 3/4 inch x I/2 inch, The robbing screen appeared to work. Sometimes there were robbers on the screen, but they couldn't find the entrance to behind the screen.
A few days later, when I wasn't watching, the robbers got in, and robbed out most of the honey and damaged the queen. I closed up the hive, but the queen was beyond recovery. She was wandering off of the combs and acting strangely for about a day. After that, she disappeared. The bees went to work raising a new queen. I thought the new queen might prove useful, so I gave them more honey and bee bread, and thought about how to make the hive robber proof.
What I came up with was:
I covered the lower entrance with screen.
I added a 3/8 inch hole near the top of the box.
hole in front.jpg
I took a 1 1/4 inch PVC elbow, and drilled 3 small pilot holes near one end at about 120 degrees from each other.
I screwed small eye screws into the holes, and then attached the elbow over the 3/8 inch hole, using 1 inch long bugle head drywall screws through the eye screws.
fitting with screw eyes.jpg
I inserted a 48 inch long fluorescent light protective cover into the PVC elbow (it fit snugly).
With this, I had a new entrance point at the top of a clear tube, nearly 4 feet above the hive box.
new hive entrance.jpg
I covered the lower entrance to make it easier for the bees to find their new exit, and watched to see what would happen.
This worked quite well. When robbers were about, they would congregate near the screened lower entrance, but they never did figure out how to get into the hive.
bees on box.jpg
The bees in the box adapted to the new entrance fairly well. I added a piece of duct tape to the top rim, to make it easier for returning bees to find. I also added a 1/8 inch drain hole at the bottom of the elbow. The bees would walk up and down the tube. They were fun to watch.
I suspect the reason this worked was that even if a robber found her way into the hive, she wouldn't be able to communicate the location of the entrance to the other bees accurately enough that they would go to the top of the tube, as opposed to the front of the hive.
The new queen emerged, mated, and began laying. I introduced her into a different hive, and the poor little colony raised another queen, who also appears to have mated (on October 20, when we had a very warm day). So I gave them lots of food, insulated the box, and we will see. I doubt very much they can survive the winter, but as it is I have nothing to lose by letting them try.
I suppose a regular piece of PVC might work as well as the transparent tube, but the initial idea I had was to make the real entrance hard for the bees to see. I added a thin stick to make it easier for them to climb the tube, since it tended to get slippery from condensation, especially in the mornings.
After I had this entrance in place for a while, I decided to open feed several partial frames of heavy syrup I had left over from last year. Since my real estate is limited, the only place far enough from my main hives was about 15 feet from this little hive. I had bees everywhere, and sometimes all over the box of the small hive, but they never got inside. Meanwhile, the bees in the hive went about their business.