When flowers are in bloom, bees are usually present. Bumblebees buzzing from flower to flower, inspecting each other's footprints, honeybees taking pollen back to the hive. There are times, for people stopping to inspect the flowers, that they might hear an unusually loud buzzing coming from bumblebees.

It can sound as if those bees, even though there is no nest in sight that is being threatened, are angry.

Not Rage

That sound can mean different things depending on the kind of bee, but if it's a bumblebee, that sound might not mean a person has intruded on the bees' territory. What it could be is sonication, also known as buzz pollination.

During buzz pollination, bumblebees distend their wings from their abdomen and then contract their flight muscles, causing these muscles to vibrate harshly.

Bumblebees use this maneuver because of the structure of most flowers. Many flowers have an anther, a structure that houses protein-rich pollen that insects can reach. Some plants, such as blueberries and tomatoes, have a different anther structures that make it much harder for insects to access.

Make That Pollen Rain

These plants store firmly attached pollen inside their anthers, out of reach for almost all insect pollinators. But the tremors of buzz pollination bring these plants' tightly packed pollen raining down on bumblebees, who then feed this pollen to their young and fertilize other flowers they visit.

It works out well for the organisms involved: bumblebees can access untapped food supplies, and the efficiency of buzz pollination means flowers conserve energy.

Pollination is important. It sustains around a third of our food supply. A vital part of this process is how buzz pollination serves plants' special needs, plants which we in turn savor and appreciate. People need to treat bees not as pests, but as living things that deserve our consideration and respect.

Thank you to Rachael E. Bonoan of Tufts University for reviewing this episode's script.

Sources And Further Reading:

• Inouye, David. "Bumblebees (Bombus spp.)." United States Department of Agriculture Forest Service. Accessed September 5, 2017.
• Langley, Liz. "Bumblebee Buzz Literally Makes Flowers Explode With Pollen." National Geographic. February 18, 2017. Accessed September 5, 2017.
• "Plant Morphology: The Parts Of A Flower." The American Museum of National History. Accessed September 5, 2017.