Generalist foragers, bumble bees are everywhere — and that's good

Physicist Albert Einstein once said that if bees disappeared from the earth, humans would have no more than four years left to live. What truth there may be in this statement gets us thinking about pollination and its importance.

Pollination is an essential part of plant reproduction. Pollen grains from flower anthers, the male part of a plant, must get to the stigma, the female part of the same species, through the air by wind or carried by a pollinator.

Then the fertilized flower yields fruit and seeds. Of the 1,400 crop plants grown around the world that produce our food and plant-based industrial products almost 80% require pollination by animals, mostly insects.

The various types of bees are the most important pollinators. Honey bees and the wild bumble bees are overall the chief insect pollinators. Bumble bees have stout, hairy, robust bodies, with black and yellow coloration. They are variable in size and color patterns. Largest of the 24 species in Minnesota is about three-quarters of an inch long. Being generalist foragers, they end up pollinating everything from peppers to potatoes, tomatoes and cucumbers, squash and cranberries, melons and berries, sunflowers and fruit trees, forest trees and shrubs, wildflowers and much more.

Lately, Sandy and I have watched bumble bees on our garden hosta flowers, plus prairie plants such as monarda and white prairie clover. Bumble bees forage in cool, unfavorable weather better than other bees, and search for nectar and pollen early in the spring, early in the day, and during cloudy weather.

The rusty patched bumble bee became Minnesota's state bee in 2019, and can be identified by a rust-colored patch on its fuzzy yellow abdomen. It can be found in grasslands and prairie areas in the Twin Cities and beyond.

While leading nature interpretation walks, I sometimes stop to pet a bumble bee drinking nectar and collecting pollen on a flower. Yes, it's safe to use a finger to gently stroke a feeding bee. This simple act leads to many questions from walk participants, and also leads to their wanting to try bee-petting themselves before we move on. Never has a child or adult been stung petting a bumble bee on one of my walks.

Bumble bees are not aggressive or likely to sting. These female workers we see on garden flowers and various wildflowers sting only when they feel threatened. Their stings, however, are painful and could be dangerous to those with allergies.

Other observations:

Jim Gilbert has taught and worked as a naturalist for more than 50 years.