Bumblebees Chew Leaves to Hasten Pollen Production

When trying to establish colonies in early spring, bees rely on flower pollen as a protein source for raising their young. Consuelo De Moraes, a chemical ecologist and entomologist at Eidgenössische Technische Hochschule Zurich, in Switzerland, reported in Science that at least three species of bumblebees use their mouth parts to snip little confetti bits out of plant foliage, and that the biting gets more widespread when there’s a pollen shortage. Experiments show that mustard and tomato plants nibbled by Bombus terrestris bees bloomed earlier than unbitten plants by days or weeks. In a caged-bee test, bumblebees trapped with non-blooming plants were more likely to poke holes in foliage after three days without pollen than a bee group buzzing among plentiful flowers. When researchers switched the bees’ situations, those trapped without blooms started nibbling leaves, too. Professor of Biology Dave Goulson, at the University of Sussex, in England, says, “I can imagine that hungry bees unable to find flowers might try biting leaves in desperation.”