Aphids Land on their Legs after Falling from Plants

Aphids can land on their feet after falling from the plants they feed on, reveals a new study.

Some insects have specialized appendages to help them glide or fall, but a common insect called pea aphids do not possess such appendages.

Pea aphids are small sap-sucking insects that live on plants in colonies containing mostly wingless individuals. Despite lacking specialized appendages, the pea aphids were able to land upright most of the time after falling from a leaf.

In order to figure out how the aphids do it, a team of researchers from University of Haifa, Israel, studied the aphid dropping behavior. The researchers placed aphid-eating ladybugs nearby so as to make the insects freefall from the leaves and drop on a cardboard covered with a thin layer of red powder.

They found that the aphids had a clear red spot on their abdomens after they fell on the cardboard. Further investigation showed that the pea aphids landed on their feet 96 percent of the time.

"What puzzled us was that the aphids did not seem to do much in order to right themselves," Gal Ribak, from the Technion-Israel Institute of Technology, said in a statement. "Their body posture remained fairly constant during the entire fall."

Using mathematical models, Ribak and his colleagues found that the aphids assume a stereotypic posture as they fall through air, regardless of their starting orientation. The air forces the body into the upright position where it is most aerodynamically stable, reports LiveScience. This improves the chances of the falling aphids to cling to the leaves encountered on the way down using their sticky feet and lowers the danger of reaching the ground.

"This is what aerodynamicists call 'static longitudinal stability,' one of the things that an aircraft engineer needs to think about when designing a plane," Ribak explained.

The findings of the study appear in the journal Current Biology.