winter survival improved by about 22% in covered hives

 

Earlier this month, I found myself questioning the results from Google Scholar while researching winter hive insulation. So I changed tactics and turned to PubMed, using the search terms insulation AND hive AND bee. Sorry, Google—but PubMed delivered a shorter, and far more useful list of journal articles.

One study in particular caught my attention: “Honey bee hive covers reduce food consumption and colony mortality during overwintering.” The research offers practical, data-backed insights that are especially relevant for beekeepers preparing colonies for winter.

The study examined full-size, 10-frame hives during the 2020 winter season in central Illinois. About half of the colonies (22 hives) were wrapped for winter, while the remaining 21 were left uncovered. To reduce location bias, the researchers distributed the hives across eight different apiaries, with roughly five to six hives per yard.

For the wrapped hives, the researchers used 4-mm-thick black corrugated polypropylene plastic sheets to cover the sides. On top of the inner cover, they added 1.5-inch (3.81 cm) foam insulation board (Owens Corning Foamular 250, rated R-7.5). To manage moisture and reduce condensation inside the hive, top entrance holes were cut into each wrap. 

The results were compelling. When paired with good overall winter preparation, insulated hives consumed less of their stored food and showed significantly better survival rates. In fact, winter survival improved by about 22% in covered hives compared to uncovered ones. 

Takeaway: If winter insulation is part of your beekeeping plans, this study strongly suggests it’s worth considering. And while the researchers used relatively modest materials, today’s beekeepers can find commercial insulation options with much higher R-values than the corrugated plastic sheets used in this experiment—potentially offering even greater benefits during overwintering.