Giant honeybees skilled at the wave: attacking hornets repelled when colony shimmers en masse.

Like fans in a stadium, giant honeybees at their nest make big, rippling audience waves, new video shows.

And the bee waves are spooky enough to drive away predatory hornets, an international research team reports online September 10 in PLoS ONE.

Giant honeybees (Apis dorsata), unlike western honeybees, form open nests without outer coverings. Thousands of the giant bees cling to each other, sometimes seven layers deep, in a mass around the home comb, says Gerald Kastberger of the University of Graz in Austria.

Wave patterns swirl across the outer layer of this mass as a sequence of bees tip their long abdomens up and down. Kastberger and colleagues filmed and analyzed some 450 bee waves, called shimmering, in two colonies in Nepal.

Moving bee patterns, Kastberger says, offer a way to study the problem of self-organization. "It's a question of organization of a team without a chief," he says.

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Smaller waves of a few bees break out as nest mates arrive and take off. When bee-hunting hornets buzz in, however, bees wave big--70 bees can flip into action in 600 milliseconds, and hundreds more join in as the pattern swirls over the nest.

As these big hornets, which hunt adult bees as food, dive toward a massive bee nest, the hornets "probably think it is a very nice supermarket where they can get everything without paying," Kastberger says.

But ripples of bee rears can change a hornet's direction. At closer than 52 centimeters, the hunter veers away as the audience waves. The bees' sudden motion may startle the predator, but whatever the mechanism, it works, Kastberger says. Waving maintains a rough no-hornet zone around the colony.

The new data support what observers have guessed, says Michael Breed of the University of Colorado at Boulder, who studies social insects. "To anybody who sits and watches these bees for any length of time, it's clear the shimmering is happening when there's a hornet around."

"I have seen the same thing in Apis cerana [a smaller bee species] in Japan," says Randall Hepburn of Rhodes University in Grahamstown, South Africa.

Besides the new paper's descriptions of predator-prey dynamics, Breed welcomes details on bee wave-making. "One of the intriguing things" he says, "is that it's really pretty."