NO CREATURE UNDER the sun--not the ant, not the honeybee, not the Type-A personality--is busier than the big, fuzzy, black-and-yellow bumblebee. Compared to the bumblebee, those other creatures are so lazy and indolent as not to deserve mention in the same sentence. That is because of one key fact: The bumblebee heats its body through exercise.
A bumblebee cannot fly until its wing muscles reach about 86 degrees Fahrenheit. It does best at about 95 degrees. Because heat departs from a small body extremely fast, the bee must drink nectar to compensate for the heat loss. Nectar is the wealth upon which bumblebee economics is based. When the colony operation is factored in, an economy emerges, with the bees balancing payoff loads against foraging costs.
Bumblebee life is so dedicated to the laws of energy that one can predict which flowers the bees will visit. At low temperatures, they lose much more heat and the bees must select blossoms that offer larger yields.
The bumblebee's nest is basically a cottage industry. In the spring, a young queen emerges from hibernation, perhaps finds an old mouse nest under some leaves, and works obsessively to start her business. At night, when not foraging, she incubates her eggs, her tubular mouth sucking nectar from a small "pot" next to her "bed" to fuel the metabolic fires. Young bumblebees cannot develop unless the temperature is maintained.
When the worker bees hatch--usually several hundred per colony--they take over the foraging operation, and, despite a frantic life of flying back and forth from the nest to the flowers, they never build more than two or three days' worth of honey supplies. The costs of flight are simply too high for saving.
By fall, if all has gone well, the colony turns out a group of new queens who will mate, hibernate over the winter and initiate the cycle again next spring.
And that's what drives the bees to charge around the yard, bumbling and probing among the blossoms.