An Introduction to Overwintering

Winter is here. The trees are bare, the grass is yellow. The temperatures are now cold enough that the bees will be clustering and unable to fly for extended periods. According to the Bee Informed Partnership, an estimated 21.1% of colonies managed in the United States were lost over the 2016-2017 winter. It’s time to take steps to ensure that your colony can survive the cold months ahead. This process is called Overwintering, and we will cover the best methods in the article below.

It is important to keep in mind that beekeeping is local. Overwintering practices will be different in places with different climates and weather conditions. It’s a good idea to connect with local beekeepers to find specific overwintering practices for your area.

When to Being Preparing To Overwinter

Winter preparations need to begin in July or August, while it is still warm and sunny outside. This is when we start thinking about winter to ensure our hives survive. Start inspecting your hives in late summer to ensure that your bees are storing more honey and slowing brood production.

Once temperatures drop below 55 degrees Fahrenheit you should strive to not open your hive. Opening the hive will break the propolis seal, which is your bees’ way of insulating their hive, and will let cool air in. Of course, there are times that you will need to open up the hive (like to feed the bees), but it’ll need to be done quickly.

Starting in mid to late summer, the Queen and workers will scale back food production. They will maintain the optimal amount of brood for the overwintering cluster that can survive on the available honey stores. Each strain or breed of bee has a different optimal brood to honey store ratio based on the climate they are adapted to. Italian bees, for example, have large clusters because Mediterranean winters are short. When Italian bees are kept in cold climates they often go through their honey stores too quickly and starve.

Ensuring Adequate Food Stores

Overwintering bees need about "one medium super" of honey according to experienced local beekeepers. This is about 40 to 50 lbs. of honey. Just to get an idea of what that amount of honey feels like, you may want to lift your hive slightly with one hand. Get one end (or even one corner) off the ground, and get a feel for the "heft" of the hive. This will come in handy later, when you suddenly panic and wonder if the honey bees have eaten all their stores. Bees and empty comb weigh very little, so gaining experience in "hefting hives" can come in handy. A lightweight hive could mean that the stores are getting low.

If your hive seems "light,” you can keep feeding with a hive-top feeder. If the day is cold, the bees will not use the feeder, but on warmer days, they will. Feed them 16 pounds of sugar to 1 gallon of water, which is a 2 -parts-sugar to 1-part-water mix (water weighs about 8 lbs per gallon). The beauty of a hive-top feeder is that you can check it and fill it on even the coldest day, as you are not disturbing the cluster.

Another important, but sometimes overlooked point is to remove queen excluders. The cluster of worker bees will be able to move through a queen excluder, but the queen cannot. This could doom the queen as the clustered bees eat their way through the stored honey. Sounds obvious, but people do forget.

Insulation and Ventilation

Wrapping hives to insulate them from the cold is done by many beekeepers. However, ventilation is a bigger need than "insulation" for an overwintering hive. The respiration of 60,000 bees contains quite a bit of moisture. Dampness can easily result in hypothermia and can kill hives at surprisingly mild temperatures. Hives with screened bottoms likely have all the ventilation required. Having an entrance notch on the inner cover is also beneficial. For those who lack one or both of these items, there are some simple things you can do to improve ventilation such as placing a pencil on the inner cover towards the front of the hive before putting the outer cover on the hive.

Reducing entrances may not be required, but inserting "mouse guards" might be a good idea. It only takes one small mouse to destroy an entire box of drawn comb. Wooden bottom boards can also be equipped with 1/4-inch mesh screen mouse guards: Cut a piece of mesh to the same width as the entrance, and about 4 inches wide. Bend it in half lengthwise until it is "V" shaped, and then push it into the entrance with a hive tool. It will stay in place due to friction. Mice can make a mess of a hive, and the bees can't break cluster to drive them out, so installing mouse guards is a very cheap and good idea.

Checking Hive Condition During the Winter

Inserting a cardboard sheet under the screened bottom board of your hive for a few days can tell you a lot about the hive condition. Use a cardboard piece that will slide under your screened bottom board, but will fit between the feet of the hive. The cardboard should be sprayed with a good coating of Pam or similar non-stick cooking spray. Gourmets can spray extra-virgin olive oil from a Misto sprayer. 🙂 Do not use commercial sticky boards used in pest control. The bees will stick to the boards and will be unable to detach themselves -- a stomach-churning, heart-rending sight. Leave the cardboard in place for 3 days and see what you find. "Hive trash" will collect under the clustered bees, giving you a good idea of the size of the cluster. Hive trash is bits of wax that the bees drop as they open up sealed cells and dislodge propolis, pollen, and other junk. If you do this periodically, you can watch the location of the cluster slowly change as the bees eat their way through the stored honey. You might even see a Varroa mite or two. The easy way to tell a Varroa mite from a hunk of wax is to press on it with your finger. If it is hard, and oval-shaped, it is a Varroa mite. If it squishes under finger pressure, it is a scrap of wax, dirt, or junk. If you find Varroa, you’ll need to treat in the Spring. Do not forget to remove the cardboard after a few days, as it certainly will block the screen, and negate the ventilation abilities of the screened bottom.

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