Note to readers: For the first installment of this series on bumblebees, see "The Funny Fuzzy Bumblebee."
BUMBLEBEE QUEENS EMERGE in early spring, sometimes as early as February, from holes in the ground called hibernacula. They then start looking for food. A good food source for queen bumblebees in early spring is the pollen from willows (Salix spp.). However, if there are nectar-producing plants in bloom, they will visit these too.
Before she can start to raise a family, each queen must find a place to build a nest. If you notice a large bumblebee flying back and forth over your garden in early spring, this may well be a queen intent on finding a location suitable for raising her young.
Bumblebee nests offer us a charming example of nature’s unwillingness to let anything go to waste. The bees prefer to nest in a dark, sheltered cavity filled with soft insulating material. However, although they can rearrange materials within their nests, they don’t bring insulating materials into the nest themselves. So nature, the ultimate recycler, allows queen bumblebees to inherit the perfect nesting spots, no longer needed by the original owners. That is, abandoned mouse nests.
Brian L. Griffin, author of a wonderful little book called Humblebee Bumblebee: The Life Story of the Friendly Bumblebees and Their Use by the Backyard Gardener, tells us that once she’s found a suitable spot, the queen bumblebee builds her nest, inserting her eggs into small wax containers. Henceforth, when not looking for food, she will actually “brood” the soon-to-be bees by lying on the egg cluster and warming it with her body.
After about a week, the larvae turn into pupae, becoming adults after a total of about 25 days. Once the first crop of worker bees emerges, the queen ceases leaving the nest, letting the workers take over the job of finding food. The colony grows larger as more workers are produced, each generation bringing more food to feed more baby bees. (According to Griffin, later generations of worker bees are actually larger than the first group raised by the queen alone, because the later bees get more food than the early bees do.) Eventually a bumblebee colony can become quite large, beginning to resemble “a medieval castle with turrets and domes ever rising,” Griffin says.
But this magnificent colony lasts only until the end of summer. In August or thereabouts, the queen, who formerly laid only eggs of female worker bees, begins to lay male eggs and large queen eggs. When the males and queens reach adulthood, they leave the colony, meet, and mate. Each queen eats heartily to build up a supply of fat, digs a hibernaculum, and tucks herself away for the winter months.
This series of posts on bumblebees is taken from an article I originally wrote for Northwest Garden News.