I have now observed this three times in the last month: bumble bees acting frantic and racing about as if to avoid impending doom (and being downright testy about people being in “their” yard), on a sunny day just before a big rain storm arrives. Typically, our yellow-faced bumble bees go about their business in a busy, but relaxed and predictable manner. So, I had to wonder: can bumble bees be used as a kind of barometric indicator, to help a Druid predict the weather?
Hunting around the web, I found a report of a recent study, “RFID monitoring indicates honeybees work harder before a rainy day,” by He XJ, Tian LQ, Wu XB, and Zeng ZJ. (supports the idea of what I have observed, though the research was done on honey bees rather than on bumble bees.
Another study, by Erika Nardone, Peter G Kevan, Michael Stasiak, Michael Dixon, “Atmospheric Pressure Requirements of Bumblebees (Bombus Impatiens) as Pollinators of Lunar or Martian Greenhouse Grown Food,” (in Gravitational and Space Research 26(2) • October 2012) showed that there is a relationship between foraging activity in bumble bees and the atmospheric pressure – though the pressure differences they tested were much more extreme than the ones I am dealing with. On the other hand, much of physiology is driven not by absolute numbers or concentrations, but by the rates of change of those numbers or concentrations. So, the causes of the behaviors I have observed could easily be related to rapid atmospheric pressure changes.
I have never seen this frantic behavior in bees, going from overcast sky to drizzle, or drizzle to heavier rain, but only from brilliant sunshine to sudden, intense rainstorm. That said, the rate of pressure change might have been sufficiently daunting so as to cause a panic. If the bumble bees can sense the atmospheric pressure change preceding a storm, they might know that it will be harder to forage tomorrow, and so rush to lay in emergency supplies, just in case.
So: When bumble bees forage frantically, rain is on the way.
Tradition has it that the ancient Druids could control the weather. Perhaps a more accurate way of putting it would be that Druids have always observed subtle signs like this, and knew perfectly well how to predict dramatic changes in weather. The Wise among them would then choose when (and when not) to share that knowledge, only speaking when it might prove useful.