Unemployed bees get job taking heat.

In a previously unrecognized display of insect heroics, honeybees will cluster on a hot spot on the wall of their hives, forming a living shield to keep the next generation from cooking.

"Thermoregulation is a big deal," explains Philip T. Starks of the University of California, Berkeley. With a lot of fussing, honeybees manage to keep their brood comb at 34 [degrees] to 36 [degrees] C year round, despite the ups and downs of outdoor temperatures. Researchers knew that bees prevent overheating by fanning their wings, and sometimes by spreading water and then wafting air across wet spots for evaporative cooling.

Now, Starks and Cornell University's David C. Gilley have discovered a new temperature trick. The researchers put heating pads against the outside of various sectors of eight laboratory beehives. When temperatures rose near the honeycombs, bee numbers almost quadrupled on the overheating wall.

When the researchers applied heat near the precious combs holding the youngsters, bees on nearby walls increased almost sevenfold, they report in the September NATURWISSENSCHAFTEN. "The brood comb contains the hive's future so it's no wonder the adults protect it," Starks says.

The bee shields did absorb excess heat, Starks says. Colonies buzzing with lots of bees managed to keep the percentage temperature rise in their brood comb down to less than half what it was in depopulated colonies that couldn't muster much of a living shield.

Starks doesn't think that heat protection is diverting bees from other jobs so much as rallying taskless bees. Despite their proverbial busyness, he says, only about half the bees in a hive are obviously working at any one time. As he puts it, "Heat-shielding also provides a potential function for the so-called unemployed bees."