Froghopper Bug Crowned "World's Greatest Leaper"

By John Roach
for National Geographic News
July 30, 2003

A sap-sucking bug that coats plants with wads of foamy spit has been crowned the insect world's greatest leaper. It has more jumping prowess than fleas, out hops the springiest grasshoppers, and clears the high bar more quickly than bush crickets.

Philaenus spumarius, commonly known as a froghopper or spittle bug, is a mere 0.2 inches (6 millimeters) long, but employs a novel catapult mechanism to launch itself upwards of 28 inches (70 centimeters) into the air.

"They do jump a heck of a long way," said Malcolm Burrows, a neurobiologist in the zoology department at the University of Cambridge in England.

The bugs are found in woodland edges and grasslands the world over. Developing young create a frothy mass commonly known as cuckoo spit on plants in the early spring and summer to hide from predators such as ants. Adults live in the open and leap when threatened and to go between plants in search of food.

Burrows, whose primary research interest is in how animals use the individual cells in their brains to generate movement, stumbled upon the froghopper's leaping agility while looking for an insect model to clear the next hurdle in his work.

What he found was an insect that accelerates from the ground with a force that is 400 times greater than gravity. For the sake of comparison, we humans jump with a force that is two to three times that of gravity.

"[The froghopper] experiences something like 400 g's," said Burrows, whose research on the froghopper appears in the July 31 issue of the journal Nature. "That's a lot. We pass out when we experience about 5 g's." Merriam-Webster defines g as a unit of force equal to the force exerted by gravity on a body at rest and used to indicate the force to which a body is subjected when accelerated.

William Heitler, a biologist at the University of St. Andrews in England, said the work by Burrows is well done and the results impressive. "I've seen froghoppers in my garden and knew that they could jump well, but I had no idea that they were such absolute champions," he said.

Catapult

The animal kingdom possesses two basic body designs that enable certain creatures to leap away from their predators, launch into flight, or spring from place to place in speedy fashion.

The long legs of animals such as kangaroos and frogs give them levering power that allows them to jump with ease. Short-legged hoppers rely on the release of stored energy in a rapid catapult action, Burrows explains in his paper.

The insect world takes advantage of both designs. Crickets use the leverage provided by their long legs, fleas store energy to power their short legs, and grasshoppers combine features of each. Froghoppers, which have relatively short legs, catapult, said Burrows.

Continued on Next Page >>


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