Can't stand the heat

A honeybee colony is a model of unity and selfless cooperation. Bees work together to tend their queen, forage for food, and maintain the colony. And when the colony's young are endangered by cold weather, worker bees come to the rescue. They form a cluster around the larvae and generate heat by vibrating their strong flight muscles. The core temperature of the cluster rises rapidly, incubating the youngsters.

But this act of sisterly care can also become a deadly weapon. Honeybee colonies are beset by predatory wasps and hornets, which prey on honeybees to feed their own young. When patrolling bees spot an approaching wasp, they surround it, creating a so-called heat ball. Inside the ball, temperatures can reach 113 degrees Fahrenheit-hot enough to kill the invader.

How do the bees survive the heat? Tan Ken, a honeybee specialist at the Xishuangbanna Tropical Botanical Garden and the Eastern Bee Research Institute of Yunnan Agricultural University in China, and his colleagues discovered that the lethal temperature limit for honeybees is about nine Fahrenheit degrees higher than it is for wasps--a small margin, but enough to do the job. (Naturwissenschaften, forthcoming)

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