What is a double screen? A double screen is just what its name implies, two screens divided with a wooden frame in between.
Double screens are useful for swarm prevention and creating a cell-building unit above a queen-right hive when raising queens. A double screen has three close-able openings to allow bees above it to access the outside world. Two nucleus colonies can be placed above it or one 10-frame box. The openings will allow this option.
If you see signs of swarming activity, as indicated by the construction of queen cells positioned on the bottom parts of brood frames, the freshening of queen cups with new white wax visible on the their outer parts, a pollen and or honeybound brood nest, and/or a reduction in foraging activity, your colony is probably going to swarm. The double screen can be helpful in this situation.
If your colony has gone into swarm mode, set a hive body next to your colony; remove the frame with the newly constructed queen cells. Examine the cells to determine if they contain larvae. If capped queen cells are present, remove all but the two best looking cells. (The other cells may be used if needed in other boxes or splits.) The “best looking” cells will be the largest, with the most stippling on their surface, probably indicating they had the best food and care prior to being capped over.
Be sure to do a close examination of this frame and make sure your queen is not on the frame. If she is, either cage her temporarily (plastic or metal hair-clip-style queen catchers work good for this) or move her to another frame. Move this frame to the center of the box that will go on top of the double screen.
Select two other frames containing brood in various stages (with clinging nurse bees) and place these in the box as well. Next, move two more frames with pollen and honey and place these on the outsides of the other frames. Finish filling this box with frames of drawn comb if available, blank foundation if not.
Select some frames with clinging nurse bees and shake these into the new box as well. You want a high ratio of nurse bees in this box. This box will need to be fed as you will not have foraging bees present. This can be done with a division board feeder placed in the box on the wall, or with the addition of some kind of top feeder. Replace the frames in the box you took the resources from with either blanks or drawn comb. If you confined your queen during these manipulations, release your queen back into the box she came from.
Place the double screen on top of the queen-right colony below and set your newly constructed box on top of the double screen. Open the entrance on the double screen that is 180 degrees opposite the box below.
Any foraging bees you have moved to the top box will return to the colony below and the nurse bees will stay with the brood and queen cells. The first queen to emerge from the cell will kill the other queen that has not emerged. She will harden over the next couple of days and then take one or more orientation flights. Finally, she will fly to a drone congregation area to mate with 10-20 drones. She may take mating flights on successive days depending on weather conditions and her success in mating.
When she returns to the hive she will begin to lay eggs. This colony is now ready to move to its own bottom board. Now you have a new colony without having had to chase it when it would have swarmed. You have also tricked the parent colony into thinking that they have swarmed. If something happens to the virgin in the top box and she does not return from her mating flight you can simply remove the double screen and recombine the colony, while still having prevented the swarm.
Double Screens for Cell Builders
If you graft queens, you will need a place to put the cells so that nurse bees will feed and care for them. A double screen can be used to create a cell building unit over a queen-right colony. The box over the double screen is stocked much in the same way you do it for swarm prevention, but without the addition of naturally occurring queen cells. To be safe you should not stock this unit with eggs or young larvae either. The reason being, if the bees decide to construct an additional queen cell on a frame below your grafted cells, and this queen emerges before you remove your grafted cells, she could kill your whole graft.
This unit also needs to be stuffed with nurse bees and fed heavily. You may also consider not opening the door to the cell building unit for two days. Grafts are introduced 24 hours after construction of this unit.
We think double screens are pretty handy to have around!