Pros and Cons of helping bees with temperature and humidity control within the hive
Humans tend to anthropomorphize their bees, which is a big word to say they like to lend them human characteristics or identify with them.
While it comes from a good place and is a sign of empathy, compassion, and caring for the bees, it often gets in the way of remembering that the superorganism is highly complex and tightly organized through intricate mechanisms that we are only beginning to understand. Our human needs and human solutions do not match those of insects that communicate through pheromones and chemical messages and need specific temperatures and levels of humidity to raise their young. That's why we need to be more mindful of the superorganism's complex climate control mechanisms and try to refrain from intervening too much…In reality, bees are master climate controllers and don’t need our clumsy help.
Well-meaning screened bottom boards and wide open entrances actually interfere with the bees' climate control work, and even increases risks of robbing or Small Hive Beetle infestations, and generally make it harder for the colony to thrive, so it's best to avoid them.
Why should we let the bees control their environment on their own?
Even small fluctuations inside the colony can weaken and retard developing bees. That’s why when we open our hives, house bees have to cover the brood with their bodies and continue activities to restore the heat and/or humidity among the brood combs until the required temperature and level of humidity are restored to optimal levels, which can take days after an inspection.
Because of that, brood nest temperature and humidity levels are of extreme importance to the colony and are controlled with utmost precision, so climate control in hives is definitely an area where our intervention usually does more harm than good. That's because our ideas of what constitutes acceptable temperature, humidity, and ventilation do not reflect what is acceptable or required for the bees, and vice-versa.
On one hand, humans typically enjoy temperatures in the 70s and 80s Fahrenheit, with low levels of humidity (20-40%), but can sustain much lower or higher températures or levels of humidity without adverse effects.
On the other hand, bees need much higher and constant températures (90-95F) and levels of humidity (50-60%) to raise their brood optimally and promote the overall fitness of the colony, and anything outside of their optimal range will prevent healthy brood rearing. Below 50% humidity, eggs won’t even hatch as they desiccate (which is also why we ought to minimize the time we hold uncapped brood combs outside of the nest). In addition, higher levels of humidity significantly decrease varroa mite reproduction levels and are actually desirable during brood rearing season (Varroa Destructor is a formidable pest of the honey bee).
How do honey bees control their climate?
In hot weather, they will circulate the air within the hive with mastery to adjust it exactly to their needs, whether it is to dehydrate the nectar they collected and turn it into honey, or to bring the temperatures down within the brood's nest.
They are able to decrease temperature by simultaneously evaporating water and creating currents of air, or increase relative humidity in the nest by evaporation without air circulation.
They can also create micro-climates and selectively decrease relative humidity around the honey combs during nectar flow so they can dehydrate the nectar and produce honey that won’t ferment by raising the temperature within the colony and producing currents of air to transport humid air outside the hive entrance.
When both ambient temperatures and relative humidity are high, honey bees partially evacuate the nest, clustering at the nest entrance in order to facilitate température and humidity control.
We see bees bearding by the thousands on the outside of the hive during the Summer, and think that the bees are too hot and that we need to help them, when in fact the conditions inside the hive are kept at optimal levels, and the bees are simply optimizing the air flows and température levels by keeping bodies on the outside and fanning to help with climate control. Bearding in the heat is actually a good thing, not to worry about.
Similarly, in the Winter they will cluster and go into torpor, or use their body as heaters to keep the queen and whatever brood is present at vital temperatures.
Can beekeepers help?
Beekeepers like to think they can outsmart the bees, and like to intervene thinking they will help them better manage their home, without really understanding the specific needs and requirements of their brood’s nest or the complex mechanisms they use to thermoregulate their hive. Because of that, they will use screened bottoms, shims under the lids, oversized entrances in the Summer, create drafts to help the bees with heat or condensation, add insulation, etc.
In addition, whatever the colony does inside the hive, we need to keep in mind it is usually progressive to avoid temperature and humidity shock. When we intervene to “help” our bees, our actions often create an abrupt or uncontrollable change within the colony that may take them a long time and a lot of resources to rectify, inadvertently setting them back and potentially preventing them from thriving.
But, as mindful beekeepers, we should ask ourselves: do these well meaning manipulations even help, or are they actually counterproductive, and should we stop trying to intervene in their climate control mechanisms? You know our answer....
So here is our advice for today:
Keep entrances as small as possible without creating huge traffic jams to minimize hot and cold weather intrusion and optimize temperatures and humidity levels in the brood’s nest. It will also make it easier for the guard bees to defend the colony from invaders, robbers, or Small Hive Beetles.
Build hives out of wood as thick as possible to increase the insulation factor and better replicate natural conditions
Allow for weather breaks: airflow and shade above the hive roofs in Summer and windbreaks in the Winter
Minimize frequency, length and depth of inspections at all times, and only inspect when you really need to.
Avoid screened bottom boards, large entrances, empty space directly above the brood’s nest, shims and all other sources of draft
In vertical hives (like Langstroth), use tray feeders or ekes or empty supers above the inner cover to feed without exposing the brood’s nest to the elements and to provide a layer of air insulation
Make sure bees always have a safe continuous water source fairly close to your apiary (but not too close to the hives or they won’t take it)
And above all: trust the bees, they know what they are doing much better that we do!