Every fall, beekeepers begin to fret about how their bees will survive the cold air temperatures of winter. One of the astounding things about European 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.

But many beekeepers want to tip the odds in favor of survival even more, so they take the trouble to insulate their wooden boxes, add entrance reducers and upper entrances. Some beekeepers even add a

Hive with quilt box

A hive with a quilt box installed; each part of
the quilt box is shown in a different color.

quilt box on top of the hive. Add a what, you may well ask?

A quilt box - it sounds so cozy! However, its main purpose is something else altogether. Its primary function is a 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 40-60 pounds of honey as their main source of calories. Metabolizing all this honey will cause them to 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. And there, just like on the side of your cold soda can on a hot summer day, condensation will form. When the condensed droplets get large enough, they will rain down on the clustered bees below.

Insulating (with a piece of foam insulation) above the inner cover will help, but it will not completely solve the problem of moisture meeting a colder surface.

This is where quilt boxes come in. A quilt box has no solid, impermeable surface. Instead, it has a piece of cotton cloth as a “floor” underneath a thick layer of pine shavings. Moisture vapor, rising up from the bees, meets the fabric and passes through it and into the shavings. Above the shavings are holes in a shim that will allow the moisture to continue to travel up, through, and out of the hive when outside conditions are right. In the meantime, the shavings will absorb the water and hold it harmlessly away from the bees. 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.

A quilt box assembly consists of three parts:

  • A shim underneath the quilt box, which has an opening the bees can use as an upper entrance and provides space for any supplemental food needed by the bees. It also provides “hang-out space” for the bees when they break their cluster during warm spells. It’s not uncommon to find a thick layer of bees hanging down from the fabric overhead inside the space created by the shim. The shim is placed directly on the top box, without using an inner cover.
  • The quilt box; a shallow box (not as high as a typical honey super, or medium box) is the best size, but both comb-honey depth boxes (even shallower than a shallow) and mediums will work. This box has fabric stapled to its underside and it is filled with clean wood shavings.
  • A second shim is installed above the quilt box to allow moisture to leave the shavings when the outside air temperatures and relative humidity allow.

Quilt boxes are having a surge of popularity right now, and there are a variety of different designs. Some of the designs are only theoretical, so it’s important to choose one that has stood the test of actual use. These are important points to consider:

1. What’s the best filling for a quilt box?

A clean, lightweight, absorbent material is best. Pine shavings fit the requirement perfectly (the kind sold as poultry bedding at farm stores.) 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. Fiberglass insulation may result in glass fibers filtering down into the combs.

2. What’s the best floor for a quilt box?

The best floor for a quilt box is clean, tightly-woven, unbleached cotton fabric. Re-purposing old sheets and other used household textiles will expose your bees to years of laundry chemical residue. Using loosely-woven cloth, such as burlap or feed bags, or using window screen, will allow small particles and dust from the shavings to rain down on your bees. Screen also poses risks to the bees if you ever must scrape them off the screen. It’s likely that their tarsi will be wrapped around the mesh and you may amputate their feet.

3. Should you put the ventilation holes in the quilt box, or in a separate shim above?

Some quilt box designs use holes in the sides of the box. But having the holes above the surface of the shavings is a better way to pass the moisture through, 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.

Hive with quilt box

Beekeeping with a quilt box in place over the winter isn’t different from beekeeping with a regular hive. The bees will quickly adapt to having an upper entrance. There is no need to close off the lower one, provided it is reduced and has a mouse guard on it. From time to time, lift off the outer cover and inspect the shavings. They will generally appear quite dry. It is unlikely to happen, but if they become saturated, just change the shavings out. When you need to lift up the quilt box to install supplemental food in the winter, simply tip it up and insert the patty or brick without removing it entirely. There will likely be bees clinging to the underside but there is no need to disturb them. If you must remove the quilt box while there are bees clinging to the underside, you can gently shoo them off with the blade of your hive tool, keeping it just a hair’s breadth – or a bees’ tarsi height – away from the cloth to avoid injuring their feet. Go slowly and let the bees fall back down into hive.

If you ever want to make quick check on whether your colony is still alive – stick your bare hand down through the shavings to the top surface of the fabric. You will feel their warmth. Be sure to repack the shavings after doing this to avoid creating an air channel in the shavings.

Entrance hole

On a cool night, water vapor leaving the hive through the vent hole condensed on the outside of the hive.

You may occasionally see a slight plume of vapor escaping the upper hole. But more commonly you’ll see beads of moisture condensing around the hole as it escapes.

When you’re ready to super up again in the spring, remove the quilt boxes. They can be left on year-round, but often bees will chew through the cloth during the summer, requiring repairs before the next winter.

Quilt Box with holes

Was it naughty bees, or a lazy beekeeper? You be the judge!