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What role does Temperature Play?

Hive in deep winter

As I write this, the temperature has started to warm and Winter is finally losing its grip on the world. My bees are also starting to build up to take advantage of the coming spring bloom. Temperature, lengthening daylight, and the arrival of available resources (pollen, and nectar) are the triggers that put a hive in motion. Even though the lengthening daylight is fairly predictable each year, temperature and the availability of resources that are driven by that temperature, can vary wildly. Temperature plays a leading role in when the bees will be able to leave the hive, and the availability of when the resources the bees are looking for can be found. It’s a good idea to monitor spring forecasts and modify your spring management accordingly. Observing how spring is unfolding each year is a much better guide than checking off hard dates on the calendar.

The conditions your bees have to weather and timing will change depending on where you live in the world. I live in northern Utah, USA, and our temperatures will typically get down into single digits on the Fahrenheit scale, but rarely below 0 and not for very long. Summer, on the other hand can range up into the 100s and stays fairly warm. We have a very dry climate and humidity stays fairly low.

First, we need to understand what the bees like as far as the Temperature goes. To raise their young, they need a humid 93ish degrees. So, the parts of the year when the temperature is cooler or warmer than 93 degrees requires them to regulate the temperature and humidity to meet that desired target. In the fall as the temperatures begin to drop and the daylight diminishes, the hive starts raising its “winter fat bees”. These bees can stay alive for several months and last thru the winter. The health of these “winter fat bees” can mean the difference in whether this hive will survive the winter or not. In hives outfitted with temperature sensors through the winter months in a nearby state of Montana (Montana State University), the average temperature inside the hive varied some b

ut averaged about 70 degrees through November, December, January, February and into the first of March (In Utah I believe this begins the end of February, first of March). ​​But the moment that the hive started expanding their brood-laying in the hive, the temperature went up to a constant 93 degrees. This of course requires a big increase in energy requirement and thus food consumption, to maintain that temperature, when it is still very cool outside. The timing of this temperature bump may vary depending on your location but occurs in all hives. This is a critical stage for the hive and is when most hives will starve to death. The hive will run out of food trying to maintain that higher temperature as they start to increase their brood rearing in preparation for spring (they double the honey consumption of the earlier winter months). But the world outside isn’t providing any of the nectar resources they need. So, this is a time for critical monitoring to see if they are running low and offer some supplemental feeding if necessary. The bees will experience temperatures warm enough to fly when it’s 45 degrees or warmer and will start to find pollen on trees, willows, etc. around President’s Day in my neck of the woods (February 20). This is what will trigger the beginning of their expanded brood laying. Some beekeepers will start feeding a 1:1 or 2:1 sugar syrup (1:1 most closely mimics the sugar to water ratio in nectar they find in flowers, but many commercial beekeepers don’t want to mess with different formulations and find adequate results using the thicker syrup year-round) and pollen substitute to stimulate early constant brood rearing (the bees will react to the availability of the needed resources). If you start supplemental feeding you have to continue providing it till they are finding adequate amounts to sustain themselves on their own, or you run the risk of them starting to expand their brood nest and then have to abandon a large part of it because they all the sudden don’t have the resources to support it (because you stopped prematurely in providing it; a common beekeeper error). Bees will start to cluster at about 57​​ degrees huddling together flexing their wing muscles to generate heat. The colder it gets, the tighter they will cluster together keeping the center of the luster a toasty 93 degrees for the queen and a

ny brood they are still trying to raise. They will cease leaving the hive for any reason, except to die, when temperatures go below 40-45 degrees (even to relieve themselves). They will hold their waste until there is a day with temperatures warmer than typically 45 degrees to leave the hive and evacuate their bowels (This is called a Cleansing Flight, or yellow rain day). On days, it finally gets warm enough you may see a large burst of flying bees for a short period as everyone rushes out to finally relieve themselves. During the Summer a worker bee can fill a 1/3 of their abdomen with nectar they collect in their honey crop (a pre-stomach storage area). During the winter, they can fill 1/3 of their abdomen with their waste in the rectum. This is why it’s important to do any fall supplemental feeding as early after your honey harvest as you can and use a 2:1 sugar to water ratio, so they have the time to mature and evaporate it into honey with the right water content (about a 14-17%). This is the right amount of water to sustain life during the winter without causing a lot of liquid waste and the waste volume they have to hold during the winter is minimized. If you continue to feed them into late fall or use a 1:1 syrup, it may cause them to defecate in the hive during the winter which brings a lot of disease issues with it. As the fall temperatures drop, so does the brood rearing and cluster size till early December when they will reach their winter cluster size with hopefully enough food to sustain them till spring nectar becomes available. Temperature is a key variable to keep an eye on all year long to give you a gauge of what the bees are trying to do and what you should do to support their efforts.

Watch and learn from observation of your own hive. The better you understand

them, the more success you’ll have working with them.


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