In Canada, most honey bee colonies are overwintered outside (CAPA, 2022). Given Canada’s cold winter climate, there is a need to protect colonies during the winter by wrapping or covering hives. There are multiple options to choose from when deciding how to best protect colonies from chilling winds. Depending on the choice, wrapping hives will prevent drafts and help with thermoregulation. This week’s blog will discuss common winter wrapping options in Canada, provide insight to help beekeepers get ready for winter, present alternatives to winter wrapping, and discuss the impact of climate change on overwintering.
Winter is Coming: Options for Winter Wrapping Hives
Winter wrapping is an important component to beekeeping in
Atlantic Canada. Wrapping hives for the winter will protect bees from chilling
winds and help colonies retain heat. There are multiple pre-made covers
available for purchase that range from materials such as corrugated plastic,
treated paper, or foam. Examples of commercially made covers include the Bee
Cozy and the Easy on Cover, which are designed to fit Langstroth hives.
Despite the availability of commercial covers, many
beekeepers develop their own way of wrapping hives with various materials, or
even make their own covers that can be used for multiple years.
The type of material is the most important consideration for
winter wrapping. Different materials have different purposes for protecting
hives in the winter. Black material is commonly used to promote heat absorption
from the sun (Sammataro
and Avitabile, 2021).
Some beekeepers choose to use tar paper or roofing paper, as the black color
absorbs sunlight to passively warm colonies on sunny days. One issue with black
paper is that moisture does not pass through easily, and water can build up in
the colony. Generally, black paper is a good option for the winter temperatures
found in Atlantic Canada, but not the best for extreme cold such as in the
Prairies.
Some materials will provide insulation to the hive. These
types of materials help colonies retain heat when ambient temperatures are low.
Insulating wrap, such as plastic bubble wrap, helps retain heat generated by
the bees, but heat from the sun cannot be absorbed as easily (Sammataro and Avitabile, 2021). Like tar and roof paper,
insulating wrap may also trap moisture inside the hive. A popular option in
Atlantic Canada, is to combine black plastic wrap and insulating wrap to
provide both heat absorption and insulation.
In addition to wrapping hives, beekeepers may put insulating
and/or absorbent materials in a quilt box over the inner cover and under the
lid to absorb moisture. This helps prevent condensation from dripping into the
hive (Sammataro
and Avitabile, 2021).
Common materials used to insulate and/or absorb moisture include wood shavings,
straw, and Styrofoam.
Current research demonstrates that traditional methods of
winter-proofing hives are effective for decreasing food consumption and
overwintering survival compared to identically managed hives without winter
protection (St. Clair et al. 2022). The study by St. Clair et al.
covered honey bee hives with corrugated polypropylene board and topped them
with foam insulation. Overall, the study provided updated evidence for the
efficacy of these types of hive coverings.
Instead of wrapping hives, some newer hive materials, such as
polyurethane, provides more insulation than traditional wooden hives. A study
done by Alburaki and Corona (2022) demonstrated that polyurethane hives
maintained a significantly higher overall temperature than wooden hives with a
significantly more optimal relative humidity compared to the wooden hives.
Improvements to modern hives, including hive material, have great potential to
reduce honey bee overwintering loss. Additionally, polyurethane hives will
maintain structural integrity for many years, they do not rot or mold because
of their good moisture resistance, they help maintain optimal temperature in
the winter and summer, and they are easy to assemble and disassemble (Eldarov et
al. 2021).
Remember to check what other local beekeepers advise for
winter wrapping. There are multiple options to choose from, and it can be a
challenge to know what will work best. If trying a new wrapping option, it may
be wise to experiment with a few colonies first before transitioning an entire
apiary or operation.
In addition to winter wrapping, changes in climate can
impact overwintering success. Seasonal weather conditions affect both forage
availability and thermoregulatory success, and thereby directly and indirectly
influence honey bee health (Schweiger et al., 2010). During
the growing season, weather conditions can affect the onset and decline of
specific foraging resources, change the duration in which resources are
available, change the quality of these resources, and alter the span during
which bees can actively forage (Bartomeus et al., 2011; Scaven and
Rafferty, 2013). During the winter, ambient temperature influences the
efficiency of maintaining internal hive temperature (Dainat et al. 2012).
A study done by Calovi et al. (2021) found that hot,
dry summers reduced overwintering survival. This is likely due to reduced
forage availability, which dramatically decreases colony weight gain (Flores et
al. 2019). Additionally, altered colony behavior as a result of
environmental conditions (such as longer brood rearing) can result in increased
disease levels (such as higher Varroa levels) (Nürnberger et al., 2019).
Thus, longer summers could result in high Varroa levels in the fall, which negatively
affects winter survival (Calovi et al. 2021).
References
2022. Polyurethane honey bee hives provide better winter insulation
than wooden hives. Journal of
Apicultural Research. 61(2): 190 – 196.
Bartomeus,
I. et al. 2011. Climate-associated phenological advances in bee
pollinators and bee-pollinated plants. Proc. Natl. Acad. Sci. U. S. A.
108: 20645 – 20649.
Calovi,
M., Grozinger, C.M., Miller, D.A. et al. 2021. Summer weather conditions
influence winter survival of honey bees (Apis mellifera) in the
northeastern United States. Sci Rep. 11: 1553.
Dainat,
B., Evans, J. D., Chen, Y. P., Gauthier, L., and Neumanna, P. 2012. Dead or
alive: Deformed wing virus and Varroa destructor reduce the life span of
winter honeybees. Appl. Environ. Microbiol. 78: 981 – 987.
Eldarov,
B. A., Mutieva, H.M, Eldarov, I.B. 2021. Assessment of wintering of the
Caucasian bee in polypeneurethane and wood hives from a comparative
perspective. AIP Conf. Proc. 2442 (1): 020001.
Flores,
J. M. et al. 2019. Effect of the climate change on honey bee colonies in
a temperate Mediterranean zone assessed through remote hive weight monitoring
system in conjunction with exhaustive colonies assessment. Sci. Total
Environ. 653: 1111 – 1119.
Nürnberger,
F., Härtel, S., and Steffan-Dewenter, I. 2019. Seasonal timing in honey bee
colonies: Phenology shifts affect honey stores and varroa infestation levels. Oecologia.
189: 1121 – 1131.
Sammataro,
D., and Avitabile, A. 2021. A beekeeper’s handbook: fifth edition. Cornell
University Press.
Scaven,
V. L., and Rafferty, N. E. 2013. Physiological effects of climate warming on
flowering plants and insect pollinators and potential consequences for their
interactions. Curr. Zool. 59: 418 – 426.
Schweiger,
O. et al. 2010. Multiple stressors on biotic interactions: How climate
change and alien species interact to affect pollination. Biol. Rev. 85:
777 – 795.
St.
Clair, A.L., Beach, N.J., and Dolezal, A.G. 2022. Honey bee hive covers reduce
food consumption and colony mortality during overwintering. PLoS ONE.
17(4): e0266219.
Connecting with ATTTA
Specialists
If you’d like to connect
with ATTTA specialists or learn more about our program, you can:
visit our website at https://www.perennia.ca/portfolio-items/honey-bees/
Email abyers@perennia.ca