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Falling Ants 'Fly' a Zigzag to Safety

February 12, 2005|Thomas H. Maugh II | Times Staff Writer

Ants living in the tops of trees in the Peruvian rain forest have developed a unique technique to control their fall if dislodged.

Even though the insects do not have wings, ants that fall are able to glide back to a tree trunk and grab onto bark, a team headed by ecologist Stephen P. Yanoviak of the University of Texas Medical Branch at Galveston reported this week in the journal Nature.

Squirrels, lizards, frogs and snakes have all been observed gliding from tree branches, but the new report marks the first time that such behavior has been observed in wingless insects.

The ants have introduced their own twist. Unlike other species, they fly backward, landing rump first on the trees.

The discovery was "completely unexpected," said Yanoviak, who said he stumbled upon the phenomenon.

Yanoviak was working in the rain forest canopy near Iquitos, collecting mosquitoes for a study of the transmission of equine encephalitis, when he brushed off some ants crawling on his arm. He noticed that, instead of falling all the way to the jungle floor, the insects made a sharp turn and landed back on the tree from which they had fallen.

Subsequent studies have shown that about 85% of the ants make it to the safety of a tree. But Yanoviak and his colleagues are not certain how the creatures can glide and make such sharp turns when, unlike other gliding species, they have no flaps that could serve as wings.

They do have long, slightly flattened hind legs, which, when combined with abdominal movements, might allow them to reorient in midair. They also have an unusual flattened head with flanges that could act as a rudder.

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