How Do Honey Bees Prepare For Winter?
Excerpted from: HOW TO OVERWINTER BEES IN A NORTHERN CLIMATE
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What do the bees do naturally during cold periods and winters? Let's make sure that we do
nothing to help them gets in the way or impedes their natural methods.
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When daytime temperatures fall below 57° Fahrenheit, they retreat to their hives and cluster
together around the queen, and next to their honey supplies, to stay warm as the temperatures
outside get colder.
As the days get colder and the nights grow longer the bees start preparing themselves for
the long, cold winter. The brood nest gets smaller, the honey stores, once relegated to the
outer friames and high above the brood nest now invade the brood frames making each frame
heavy with energy rich carbohydrates.
The cracks and crevices that once provided cooling ventilation are now tightly sealed with
propolis and the drones that were so pivotal to the local area’s bee propagation
are now deemed unnecessary and are unceremoniously kicked out.
One of the more amazing changes that happen to a bee colony entering the winter months is the
development of winter bees. These are bees with enlarged fat bodies that allow
survival for months on honey or sugar alone and even give the bee the ability to produce protein
rich brood food in an absence of fresh pollen.
This period of winter bee rearing is probably the most important few weeks of the bee year. There
will be no other chances to increase the winter bee population, if they miss this small window or
for any reason they are unable to create a sufficient amount of these “fat bees”, the colony is on
borrowed time.
The process the bees use to develop these winter bees is similar to the process used to create a
queen bee. When creating a queen, it is the lack of pollen and nectar and the surplus of royal jelly
fed to the young larvae that allows the ovaries to fully develop and creates a distinctly different bee.
When creating a winter bee it is the relatively low level of protein fed to the larvae that kick up the
production of fat bodies and the compound vitellogenin, a glycolipoprotein with properties of sugar,
fat and protein that give nurse and winter bees a greater immune system and allows winter bees
to consume and dispense nutrients that aren’t readily available in the hive or the field.
This incredible use of external conditions to implement epigenetic changes is truly one of the most
fascinating things about this lovable creature we’re all trying to keep alive.
At this point the brood level is severely diminished and the egg laying portion of the year is usually
complete.
When the outside air temperature falls into the low 50’s Fahrenheit the bees huddle together to
create a temperature regulating cluster that expands and contracts to keep the cluster at a very
specific set of temperatures. When there is no brood present the cluster temperature usually stays
about 85° F, when there is brood present the thermostat is raised to 93° F.
This fact is why cold weather brood manipulation and early pollen feeding can cause havoc inside
the hive as the bees try to maintain temperatures high enough for the brood to develop despite
not having enough bees or food to contribute to this effort.
The outer layers of bees detach their wings from the muscles that move them, allowing them to
vibrate those muscles to generate heat. When the outer layers become too cold they are moved
toward the center of the cluster to warm up while a new set of bees takes up the heat generation
job.
This method of heat maintenance is not the furnace that spreads warmth throughout your house in
the winter, rather than heat the entire cavity of the hive the bees only expend enough energy to heat
the cluster.
The warm, moist air that does leave the cluster rises inside the hive until it reaches a cold surface,
where it condenses into water droplets and threatens the colony. If this moisture builds up enough,
it will drip onto the colony, reducing their ability to maintain proper temperatures and threatening a
quick, cold death.
The cluster will work its way throughout the hive following the honey, but primarily moving upwards,
presumably following the heat rising from the group. This movement is slow and sometimes not
possible due to frigid cold, causing colony deaths due to starvation even when there is ample honey
to the side, below or even above the cluster.
This is why the ubiquity of sugar is an essential element to any northern honey bee colony’s survival.
It’s not just enough to have the right amount of honey or sugar, it has to be in the right place for easy
access.
During these clustered months, the bees eat enough to maintain, which, obviously brings the
requirement of ridding themselves of waste. Their ability to “hold it” is profound but not limitless,
and the buildup of bee poop inside the hive can bring on unhealthy conditions. That is why it is so
important to allow the bees access to the outside at all times, no matter how many dead bees
are clogging the main entrance, by giving them a secondary, or “upper” entrance.
When the outside air temperature climbs above 50&geg; F and the sun is shining, the bees race
outside to paint the snow with their orange waste, sometimes covering the lids and sides of the
boxes as the need grows too great to wait another second.
If the amount of poop on the lids surprises you, know that it is a good thing as it means a reduction
in overall stress on the colony.
As the days start finally to grow longer and the mercury begins to rise, those fat bodies existent in
the winter bees exhibit another area of importance for the colony’s continuation and growth. The
queen starts laying small patches of brood and even without incoming fresh pollen the fat nurse bees
produce protein rich royal jelly to feed the new spring bees.
The brood patch grows slowly with the length of the day until the first abundant sources of pollen
herald the end of winter.