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Tim Lockley: The humble bumblebee is a busy pollinator

Up until about a century ago, they were called humblebees -- not because they were humble but because they made a rather pleasant hum when they flew from flower to flower.

Darwin referred to these fascinating, fat, fuzzy fliers as humblebees. In the first great opus on bees, published in 1912, the name humblebee was used.

About that time, we were starting to fly ourselves, and a new type of human being was beginning to arise amongst our populations, someone called an aeronautical engineer. Partly based on Bernoulli's principles of flight, these engineers began to profligate the myth that it was scientifically impossible for these bees to fly. The faster and sleeker our aircraft became, the more bumbling these creatures looked with their tubby bodies and relatively small wings.

The proof of their ability to fly is obvious to even the most cavalier observer. But how? It wasn't until the late 1970s that entomologists finally found the answer. Almost anything can fly if enough energy is available. And energy is the key to the flight of the bumblebee (especially playing it on a trumpet). In order to get their wings to flap at a rate of 200 times a second (about the RPMs of the average motorcycle engine), bumblebees transfer energy from their abdomen (which is pretty much dead weight when they're flying) to their wing muscles, allowing them to reach speeds up to 20 kilometers per hour.

This requires a lot of food. A bumblebee with a full stomach is less than an hour from death by starvation. They eat nectar and pollen. The nectar is carried back to the in a honey stomach. The pollen is secured in pollen sacks on the hind legs. They can carry half again their own weight in pollen and still fly.

To save them the embarrassment of wasting time (something all bees are loath to do), bumblebees have evolved smelly feet. Like most insects, bumblebees are coated with an oily film that makes them waterproof. To this film, they've added a chemical signature that they leave on any flowers they've visited. Other bumblebees can smell this chemical and realize that it's going to be empty of pollen or nectar and they won't land. Pretty neat. Bumblebees also use their smelly footprints to put out the welcome mat for returning bees. It helps to guide them back to the entranced of their nest.

A bumblebee nest doesn't survive more than a year -- some as little as six weeks, depending on the species. Only the queen survives the winter. In the spring, she'll emerge from the ground and seek out an abandoned rodent burrow or some other ready made hole to begin her nest. A few species will weave together tall grasses and establish their nest on the ground inside the "tent." Bumblebee nests are a lot smaller than those of other bees. Most of that is because there are never more than 400 or so workers in even the largest colony.

About the only time a bumblebee will become aggressive is when her nest is threatened. Unlike honeybees, an angry bumblebee can continue to sting even after she's run out of venom. By that time, most invaders have gotten the message and moved on.

Years ago, when hay was cut by hand, field workers would seek out bumblebee nests to steal their honey (a small amount compared to honey bees). They'd eat the comb and then use the attacking bees as an excuse to stake a break from their hard manual labor.

Unfortunately (for us and them), these prodigious pollinators are disappearing right along with their cousins the honey bees. Here and around the world, there are a number of conservation groups attempting to halt the demise of the over 250 species of bumblebees. We had 46 species in North America a century ago. Around 20 percent of those have already either gone extinct or are on the very edge of that precipice. We need these little gals to keep doing what they do so well so that we can eat. Without bees, two-thirds of our crops would not be pollinated. Look up some of these organizations on the Internet and get involved in saving these humble creatures.

Tim Lockley, a specialist in entomology, is retired from a 30-year career as a research scientist for the U.S. Department of Agriculture. For answers to individual questions, please send a stamped, self-addressed envelope to Tim Lockley, c/o Sun Herald, P.O. Box 4567, Biloxi, MS 39535.

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