Bumblebees Defy Odds With Swimming and Flight

The little pool in my backyard is busier than the Atlanta airport. In the late afternoon, bumblebee bombers are landing and taking off four and five at a time. Their landings are not quite touch and go. They seem to be tanking up. They rest on the water just long enough for a drink.

They are showing remarkable traits, and raising more questions than they answer.

It is urban legend that bumblebees cannot fly – a legend disproved by the obvious evidence. Nevertheless, it is true that bumblebees do not have the characteristics we normally connect to aerodynamic flight.

They seem large for their wings – somewhat like a small stone with cobwebs. They are not sleek, but covered with hairs and dragging pollen buckets on their legs. They do not seem very hydrodynamic either. Their fat little bodies look as if they should immediately sink when touching the water.

A close look reveals they are relying on surface tension to rest lightly on the water surface, denting it, but not breaking through the outer layers of water molecules enough to sink.

Upon takeoff, they seem to fly up nearly vertically, with no taxiing and no smooth, flat climb.

They can fly faster than a person can run. Recently, scientists have begun to understand more about bumblebee flight.

Bumblebee wings (two pair, lightly attached in sets on each side) are rather rigid on the leading edge, but with very flexible surfaces and trailing edges. In this, they are rather like costumer wings for kindergarten butterflies – a stick or wire with cloth attached.

Bumblebees rely on their wings for lift and propulsion, unlike modern fixed-wing aircraft. The motion of the wings is rather subtle: out, twist and return. The result is to generate vortexes in the air in a way that provides lift, thrust and directional control.

Some scientists have studied this motion by attaching small slivers of mirror to bumblebees and tracking their motion with laser light.

Military scientists are interested in this peculiar style of flight, because small insect-size robotic fliers have military uses for observation.

Bumblebee landings on water raise some questions I need to answer with further study. Do bumblebees drink from ponds and streams regularly? Is this just a dry weather and drought phenomenon?

Would bumblebees normally get enough moisture from the flowers whose nectar they harvest? Are the flowers too dry to provide enough moisture?

How curious it is that in a bumblebee hive, all the bees except the queen die off in the winter. In the spring, the queen lays eggs and begins a new hive.

Virginia’s science Standards of Learning encourage students to apply scientific concepts, skills, and processes to everyday experiences (Goal 4) and to develop scientific dispositions and habits of mind including curiosity. The study of animal behavior and habitat begins in first grade (1.7) and continues in 2.7, 3.4, and higher grades.

On the Web

Bumblebee facts: www.bumblebee.org/

Plight of the Bumblebee:

http://science.the-environmentalist.org/2007/10/plight-of-bumble- bee.html

Bumblebees around the house: http://hgic.clemson.edu/factsheets/ hgic2500.htm

Bumblebee flight research: www.physorg.com/news89459870.html

Walter R.T. Witschey is professor of anthropology and science education at Longwood University.




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