The spring time dance of bees, they survived the winter but what influences spring survival and success. I’m writing this April 12, 2022. We had a week of 70 degree days, today it is snowing and 22. I’m writing this from my perspective and experience of keeping bees in Southern and South Eastern Idaho. Our hives are wintered outdoors in the open, same place they have been all year.
I also want to ask a few questions to get your mind thinking bee biology! How long does a summer bee live? How long does a winter bee live? What outside temperatures trigger brood rearing? Once brood rearing starts, what temperature do bees keep brood at, and at what cost? What winter activities could shorten the lifespan of a winter bee?
I will get to all those answers, just wanted you to start thinking about the hive makeup while we discuss spring in Idaho. Every year can be different, but looking at weather trends and averages for the year can give us some insight as to the average normal conditions bees face. I will be focusing on April as that is when we see some of our first fruit tree blooms. With fruit trees, once they have absorbed enough heat units, they bloom regardless of what the weather is doing.
Charts have been taken from https://www.weather-us.com/en/idaho-usa/twin-falls-weather-april#temperature
Take away for this chart is in looking at what temperature bees start to forage (generally above 54 degrees). If you have enough heat units, flowers may bloom, but low temperatures limit the amount of foraging that can take place.
The center of a winter cluster is around 80 degrees (The outer edges are 40.) Once they start rearing brood, they bump it up to 95.
Depending on location, wind can even further limit the effectiveness of foraging or even if the bees leave the hive. 15mph generally stops foraging. Note how rough April can be!
We don’t tend to get a lot of rain, but when we do, bees stay home.
So now that you have had a look at the spring weather, think about how few days are actually perfect for foraging. Overwintered colonies appear to gamble a bit on when to get fired up in the spring. Build up too early, and a cold snap can take them down as they desperately try to keep brood warm and consume huge amounts of resources. This same weather may even prevent them from foraging at a time when they need the resources. Wait too late and they miss the early nectar flows.
There is one other consideration for what happens in the spring. The age of the bees in the hive. I like to say a bee only has so many miles in it, low work and stimulation= long life, start working hard, get disturbed and bee lifetime can be shortened. The chart below was done from bees in Manitoba Canada, but gives you a good Idea of the age of bees in a hive. Notice in March-May there is a turnover of Winter Bees to Summer Bees. Remember, a winter bee can live several months and a summer bee lives a few weeks. When winter bees start rearing brood, their life span really starts to drop. This explains how a hive can be packed with bees in the spring raising lots of brood and then in a matter of a week or two shrink too almost nothing. The winter bees died off before getting the replacement summer bees reared. Some hives time it right and make it, some don’t. Guess you could say some colonies play the weather lottery better than others.
I’m always asked, when should I start feeding my bees? If you start in February and the hive thinks spring has come, they may build up, raise lots of brood and be fine, or a cold snap may chill the brood and waste all the energy and ultimately kill the colony . Every year is different. If a hive has sufficient stores, I don’t push liquid feed until I see the natural sources coming on.
Hopefully you know have some insight into the spring biology. What can we do to help set the bees up for success.
Go into the winter with a strong (big cluster) heavy (lots of food) and low varroa mite numbers (winter bees raised by bees that had low mite numbers)!
This will give the bees a big enough colony with enough resources to start raising a small amount of brood early. When day time highs are consistently over freezing, bees can start raising a few bees. Remember, it takes 21 days to get those new bees up and running. You need enough winter bees around to get this done.
Keep winter bees alive for as long as possible. First off, the mite transmitted viruses shorten the bees life span, so the mite treatments you do in Aug and Sep are pretty important come spring.
The next thing is really out of your control, weather can impact how active bees are and how much honey they consume in the winter. Again, they only have so many miles, so if they are flying on a warm November or December day, they are burning miles for nothing. This next chart shows bees metabolic rate based on temperature. You can see there is a sweet spot around freezing. The bees are in their winter cluster and are using their stores as efficiently as possible. My bees in Malad (which is much colder than Twin Falls) winter better and on less stores for this very reason. When they shut down in the fall, they are done till spring. Sometimes in Twin Falls the weather is warm enough for bees to fly in December, this isn’t good for the bees long term survival. Those winter bees might not make it into spring.
Southwick, EE (1982) Metabolic energy of intact honey bee colonies. Comp. Biochem. Physiol 71A: 277-281
Last thing on this list, Is don’t bother the bees more than you need to. Below 50, stay out of the hive. If you go over to your hive in December and give a knock on the hive, you may be rewarded with a buzz. What you may not have realized is that this caused the bees to raise their alert level, burn more energy and a few miles, too many winter and early spring disturbances can shorten the life span of the winter bees.
So, give your bees the best chance of survival, realize that keeping them alive is a gamble, and we tend to say that they haven’t made it through winter unless they make it to dandelion bloom!