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Nights draw cold and we huddle together for warmth. Shivering at first and then later abuzz with motion. Keeping muscles working, keeping fuel burning, keeping our bee family warm. Welcome to The Nature of Phenology where we share the cycles and seasons of the outdoors. I’m your host, Hazel Stark.
For every human on Earth, there are about 200 million insects. In Maine, especially around May and June, that fact might be easy to believe. But in the fall when we suddenly realize we haven’t gotten a mosquito or deerfly bite in a few weeks, many of us are so relieved to be able to go outside and recline leisurely in the sun without being surrounded by screens or having to get up and run every thirty seconds, that we often forget to wonder where they all went. One of the last significant insect encounters I had this fall was in a couple of run-ins with swarms of yellow jackets, accidentally disturbed by hikers who walked too close to their underground homes. I was so focused on getting away from those often aggressive pollinators that I forgot to wonder what happens to them when we don’t see them anymore after a few hard frosts. The winter strategies of just a few of those yellow-striped insects are the topic of today’s episode: bees and wasps. [bee buzzing sound]
There are many adaptations that insects in cold climates employ to ensure the success of their species through a northern winter. Some leave only hardy eggs behind and count on their winter survival, with all adults dying off. Others tuck themselves away in protected areas, perhaps underground or behind some tree bark, and rely on their amazing capacity to produce their own kind of antifreeze so their cells don’t get damaged from sub-freezing temperatures. Honeybees and bumblebees, however, each do something quite different.
Bumblebees don’t literally put all their eggs in one basket, but they do make quite the gamble on just a few juvenile queens. These young queens are tasked with mating, then burrowing underground a few inches until spring when hopefully one of them will be able to start a new colony. All the other bumblebees from her previous colony die. Yellow jackets employ much the same strategy, which is why they can get particularly edgy in the fall when they’re really trying to ensure that they have mated before the majority of them die.
Honeybees, on the other hand, all try to survive winter by working together as a collective. Towards the end of the summer, honeybees with more fat and a more cold-resistant blood chemistry are born, replacing the summer-adapted bees that were so helpful in stocking the hive with honey. Once those summer bees die off, the winter bees replace them, and they force out the one-minded drones whose only purpose is to reproduce, they’re just about ready for winter. When the temperature drops below 64 degrees Fahrenheit, the collective clusters together, with the honeybees on the outside of the ball densely packed and the ones on the inside a bit more spread out. The density of this ball of honeybees changes with the temperatures, making an insulative layer that rivals mammal fur in effectiveness. If it gets much colder, the bees at the center pump their powerful flight muscles, essentially shivering and burning energy from the honey they stored to actually produce heat. If they don’t have enough honey saved for the winter—sometimes 60 pounds is necessary—the ball of bees dies from the outside of the buzzing ball to the inside.
So the next time you’re considering winter survival strategies, you can take some tips from honeybees: eat a lot of sugar, dance around with some friends, and huddle together when things get especially tough.
You can find a link to the full transcript of this show as well as references, contact information, and accompanying photos by visiting archives.weru.org. You can also listen to or download our features or subscribe to podcasts. Theme music was by a pileated woodpecker, made available by the US Fish and Wildlife Service. Thanks for listening and please join us next week for another dive into The Nature of Phenology.
McFarland, K. (2004, October 3). Bumblebees Roll the Dice | The Outside Story. Retrieved November 23, 2018, from https://northernwoodlands.org/outside_story/article/bumblebees-roll-the-dice
Numbers of Insects (Species and Individuals). (n.d.). Retrieved November 23, 2018, from https://www.si.edu/spotlight/buginfo/bugnos
Shen, L. (2012, January 2). Going Sweetly Into Winter | The Outside Story. Retrieved November 23, 2018, from https://northernwoodlands.org/outside_story/article/going-sweetly-into-winter