The giant flights of the bumblebee

According to the bumblebee argument, the laws of aerodynamics prove that the bumblebee can’t fly. The Smithsonian recently referred to this bit of folklore when reporting the discovery of Michael Dillon, an ecologist at the University of Wyoming in Laramie. Bumblebees, says the Smithsonian, not only can fly – they can fly over Mount Everest:

In the mountains of western China, the researchers captured six local male bumblebees (Bombus impetuosus) in the wild at around 10,660 feet. They stuck the bees in a hypobaric chamber, and gradually sucked air out, simulating higher elevation environments with reduced oxygen and air density. They observed the bees’ behavior, recorded sound to calculate their wing beat rhythms, and analyzed wing motion from video footage. The average bumblebee could still successfully hover at about 26,000 simulated feet, and two bees flew higher than 29,527 simulated feet – that’s about 500 feet above the summit of Mount Everest.

Here’s a video of one of Dillon’s bees flying in a box:

[youtube=http://www.youtube.com/watch?v=-GrLH9Tqhpg&w=750&h=422&rel=0]

Irrefutable proof, I know. Just take his word for it. They can fly very high into thin air when stuck in a hybobaric chamber without anything else to do.

But would bumblebees fly over Mount Everest? Sadly, no. Being humans, we automatically think: bumblebees could fly higher than Mount Everest, therefore they must do it. We would! We shoot ourselves over canyons and jump out of spacecraft whenever we get the chance. But bumblebees, being perhaps more sensible than humans, most probably use this ability to carry heavy loads of pollen. Dillon says this as well, but the headline Bumblebees Carry Heavy Loads of Pollen isn’t going to win a lot of attention. He had to go with the Mount Everest gag.

How high do bumblebees fly? Dillon has found them as high as 16,000 feet, where the flowers only peeked out through the snow. At 29,000 feet, there aren’t nearly enough flowers to make the trip worthwhile for your average bumblebee.

(You can picture the bumblebees shaking their fuzzy heads over this: First they claim we can’t fly, and then they claim we can fly over Mount Everest?)

The bumblebee argument

Back to the bumblebee argument – some people say the story came from a dinner party, where someone did quick and flawed calculations. Sometimes the story features a biologist who asks an aerodynamics expert about bumblebees, then laughs when the aerodynamics expert can’t explain how they fly.

It’s all vague and  improbable, but one popular version goes that a French entomologist named August Magnan made the statement in 1934, based on calculations by his engineer assistant. There’s even a quote from his book Le Vol des Insectes that backs this idea up:

Tout d’abord poussé par ce qui se fait en aviation, j’ai appliqué aux insectes les lois de la résistance de l’air, et je suis arrivé avec M. Sainte-Laguë à cette conclusion que leur vol est impossible.

(First prompted by what is done in aviation, I applied the laws of air resistance to insects, and I arrived, with Mr. Sainte-Laguë, at this conclusion that their flight is impossible.)[1]

He also wrote One shouldn’t be surprised that the results of the calculations don’t square with reality.

I haven’t seen the original text and have no idea if this is true. The results of folklore and pseudoscience don’t usually square well with reality either, but a good story is always appreciated.

In 2006, scientists in California uncovered the mystery of bee flight in a series of experiments involving bees in helium-filled boxes. (More boxes – bees must love scientists.)

Researchers forced the bees to fly in a small chamber filled with a mixture of oxygen and helium that is less dense than regular air. This required the bees to work harder to stay aloft and gave the scientists a chance to observe their compensation mechanisms for the additional toil. The bees made up for the extra work by stretching out their wing stroke amplitude but did not adjust wingbeat frequency.[2]

We always knew they could fly. Here’s a beautiful little slow-motion film detailing the movements of a bee’s wings:

[youtube=http://www.youtube.com/watch?v=yRE2rMIXvyU&w=750&h=563&rel=0]

Why do bees buzz?

One last thing about bumblebees: you might believe that the buzzing noise comes from the bee’s wings, but the sound actually results from the vibration of the bee’s flight muscles. They decouple and vibrate these muscles to warm up – an act of thermoregulation. All bees do this to stay warm, but bumblebees in particular need to maintain a good amount of heat in their bodies for flight at low temperatures. Especially, we can assume, if they’re going to fly over Mount Everest.

See more at: The Smithsonian: Bumblebees can fly into thin air.