Listen carefully as you watch bumblebees going about their chores, and you will hear their hum. It was this humming of the wings that earned them the name of bumblebee — it comes from the Middle English word "bumblen," which means "to hum."

On observing bumblebees in flight, people are surprised that these burly giants can progress through the air with such small wings. Antoine Magnan, a French zoologist, made some very careful studies of bumblebee flight in 1934 and came to the conclusion that, because of their size, the creatures should be unable to fly.

There are many species of bumblebees. The most common kinds can be recognized by their robust shape, hairy bodies, and black and yellow markings, with a few having orange markings. Most of them are three-quarters of an inch long or longer. They live in colonies, usually in the ground and often in an animal's deserted burrow.

Bumblebees collect pollen and nectar. They use both as food, bringing them back to the nest to feed the larvae and queen. It's during their countless trips to flowers that the bees transfer pollen on their bodies from male to female flower parts, where fertilization takes place. Before a plant can produce fruit or seeds, the flowers must be pollinated.

Every year we have a multibillion-dollar job performed for us, free of charge, when this pollination work is done by bees and other insects. We have fruits and vegetables only because insects carry pollen. Of the insects, bumblebees are extremely important with their constant visits to orchards, fields and gardens.

Jim Gilbert's Nature Notes are heard on WCCO Radio at 7:15 a.m. Sundays. His observations have been part of the Minnesota Weatherguide Environment Calendars since 1977, and he is the author of five books on nature in Minnesota. He taught and worked as a naturalist for 50 years.