Overwintering successfully requires four basic things:
- Plenty of healthy bees
- A strong queen
- Plenty of stored food
- Good ventilation
If you lack one of these items, you won’t have a strong hive in spring whether you wrap or not. But if you live in a very cold climate, and you’ve met the four basic requirements, wrapping can be beneficial.
Think of it like this: if you live in a climate where it would be difficult for a healthy feral colony to overwinter, then wrapping makes sense. If nothing else, it can increase the chance of hive survival and it can give you a boost at spring build-up.
Wrapping properly can raise the temperature in the hive, reduce condensation over the cluster, and reduce drafts cause by winter winds. Done poorly, wrapping can turn the hive into a damp, disease-ridden death trap for the bees.
There are as many ways of wrapping as there are beekeepers, but once you understand the principles, you should be able to wrap with minimum expense and hassle.
Here’s a short list of considerations:
- A dark color absorbs heat from the sun. Tar paper, also called roofing paper or roofing felt, is a black, water resistant, inexpensive wrap that can be stapled or tied around the exterior of the hive. It will provide protection against rain, snow, and wind, while absorbing solar heat as well.
- A piece of Styrofoam under the inner cover will reduce condensation over the cluster. Condensation occurs when warm, moisture-laden air rises from the colony and touches the cold lid or inner cover. Since Styrofoam is a good insulator, water is less likely to condense on its surface.
- In any case, the warm moist air must be continuously removed from the hive because, eventually, it will condense—even on the insulation. It can’t be removed unless it has a place to go, so an upper entrance or ventilation port must be used in conjunction with a lower entrance or open bottom board. In other words, air must be able to circulate through the hive, bottom to top.
- A top entrance works well in winter because, besides allowing air flow, it is less likely to become blocked by snow or clogged with dead bees.
- At least one beekeeper I know uses screened bottom boards surrounded by skirts of tar paper. The screened bottom boards allow for good air flow and the black skirts act like solar collectors, resulting in nice warm air circulating up through the hive. (This beekeeper has assured me that when he sticks his hand up under the skirt he can feel the warmth. Ahem . . . )
The biggest blunders occur when the wrapping is so “weatherproof” that moisture produced on the inside of the hive cannot escape. Once condensation builds up in the hive it can drip down on the bees causing them to chill and die. Moist hives are also breeding grounds for disease. Good ventilation must be a major part of any plan to wrap.