Every fall, beekeepers begin to fret about how their bees will survive the cold air temperatures of winter. One of the astounding things about Western honey bees is their enormous adaptability to a wide range of local conditions. Bees raised in northern Maine could easily survive in Key West, Florida, and vice versa. Given healthy bees, enough food resources, and freedom from pests, a strong colony will come through the winter in good condition.
To strengthen the odds, many beekeepers insulate their wooden boxes, add entrance reducers and upper entrances, and add quilt boxes. Here, we explain what quilt boxes are, how they improve overwintering outcomes for bees, and how to use them in your own hives.
A hive with a quilt box installed; each part of
the quilt box is shown in a different color.
A quilt box sounds cozy, but its main purpose is something else altogether: The primary function of a quilt box is as a hive moisture management tool. As anybody who’s ever been out in cold weather knows, you can easily handle cold temperatures, as long as you stay dry. It’s the same with your bees.
Over the course of the winter, a colony will consume 40 to 60 pounds of honey as their main source of calories. As they metabolize this honey, they’ll give off moisture as water vapor in their breath. This moisture can amount to more than three gallons of water over the course of a winter!
The warmed air from the bees’ collective breaths will rise upward until it meets a colder surface, typically a wood inner cover. Just like on the side of your cold soda can on a hot summer day, condensation will form where the heat and cold meet. When they get large enough, the condensed droplets rain down on the clustered bees below.
Insulating using a piece of foam insulation above the inner cover will help, but it will not completely solve cold surface moisture problems within your hive. This is where quilt boxes come in.
A quilt box has no solid, impermeable surface, but instead uses a piece of cotton cloth as a “floor” underneath a thick layer of pine shavings. Moisture vapor that rises up from the bees meets the fabric and passes through it, into the shavings. The shavings will absorb the water and hold it harmlessly away from the bees. Then, when outside conditions are right, holes in a shim allow the moisture to travel up, through, and out of the hive. The shavings, being well packed, will close up the top of the hive stack so that the bees don’t freeze.
This simple idea originally came from Warre hive design, but with some modifications, works well on all Langstroth-style hive boxes.
Quilt boxes are a popular option for moisture management, and there are a variety of effective designs. Some quilt box designs are only theoretical, so it’s important to choose one that has stood the test of actual use. Check out our directions for how to make a quilt box, and consider these important points for construction and use.
A clean, lightweight, absorbent material is best. Pine shavings — the kind sold as poultry bedding at farm stores — fit the requirement perfectly. Sawdust is too dense to allow moisture to move through, straw and hay will begin to ferment if they get wet, leaves don’t absorb moisture, and fiberglass insulation may result in glass fibers filtering down into the combs.
Choose clean, tightly woven, unbleached cotton fabric, but avoid re-purposing old sheets and other used household textiles, which expose your bees to laundry chemical residue. Avoid window screen or loosely woven cloth, such as burlap or feed bags, as they allow small particles and dust from the shavings to rain down on your bees. Using screen material also poses amputation risks to your bees as their tarsi may wrap around the mesh, and you may harm them if you must scrape bees off the screen.
Some quilt box designs have ventilation holes in the sides of the box, but placing the holes above the surface that holds the shavings allows moisture to pass through easier — especially if the shavings are slightly mounded up within the open space inside the shim. This exposes the greatest amount of surface area to evaporation. You may occasionally see a slight plume of vapor escaping the upper hole. More commonly, you’ll see beads of moisture condensing around the hole as it escapes.
On a cool night, water vapor leaving the hive through the vent hole condensed on the outside of the hive.
Overwintering with a quilt box in place isn’t different from beekeeping with a regular hive. The bees will quickly adapt to having an upper entrance, and there is no need to close off the lower one, provided it is reduced and has a mouse guard on it.
Follow these quick tips for quilt box use to keep your bees happy all winter:
When you’re ready to super up again in the spring, remove the quilt boxes. While they can be left on year-round, bees often chew through the cloth during the summer — creating necessary repairs before the next winter. For more information on helping your bees survive and thrive through the winter months, explore our Beekeeping Guide.
Was it naughty bees, or a lazy beekeeper? You be the judge!