A wasp, attracted to food, dispenses with a vexing ant by grabbing it, flying backward and then dropping its cargo.
Credit: J. Grangier and P.J. Lester/Biology Letters 2011
A kind of wasp that often flees from scary, acid-spraying ants turns out to have a strong move of its own. When both the invasive Vespula vulgaris wasps and native New Zealand ants scramble to collect the same food windfall, one of the wasps sometimes swoops down and grabs an unsuspecting ant, then flies backward and drops it. The ant typically does not choose to return to the food, Julien Grangier and Philip Lester of Victoria University in Wellington, New Zealand, report online March 30 in Biology Letters.
Behavioral ecologist Monica Raveret-Richter finds the behavior intriguing and puzzling. Wasps were most likely to make a grab when many ants crowded over the food. “It’s hard to imagine the advantage of removing just one,” says Raveret Richter, of Skidmore College in Saratoga Springs, N.Y. She hasn’t seen ant-dropping in the Vespula wasp species she studies, but she normally works to keep ants out of her experiments. “Perhaps next time I set out baits,” she says “I should let some ants join in, and see what happens!”