Facial markings help paper wasps identify each other

N.Y. -- Paper wasps all look the same, right? Wrong. An animal behaviorist at Cornell University reports that the wasp's black-and-yellow uniform is not uniform at all.

One wasp, she has discovered, can recognize another through facial and abdominal markings, all but displacing the scientific dogma that insects carry out identification and communication only by employing chemicals called pheromones.

"Their faces are far more beautiful and different than you'd expect," says Elizabeth Tibbetts, a Cornell doctoral candidate in neurobiology and behavior.

Her study, "Visual signals of individual identity in wasp Polistes fuscatus ," appears in the Proceedings of the Royal Society of London B (Issue 269). This is believed to be the first study showing that wasps can visually recognize individual kith and kin through facial and abdominal markings and will visually reject unfamiliar wasps.

"They are more sophisticated than we thought," Tibbetts says.

To understand paper wasp behavior, the researcher examined life inside the hierarchical wasp society. Queens and workers form a power structure that determines how food is distributed, how work tasks are assigned and who will be allowed lay eggs within the colony. "Such a stable hierarchy would be simplified if individuals of different ranks had some degree of individual recognition," says Tibbetts.

She interrupted the societal rankings by painting wasps' faces and abdomens, altering their yellow markings. Back in the colony, these painted wasps were the victims of considerable aggression. "Wasps did not immediately recognize the alleged intruder, and fights among former friends broke out," Tibbetts says. Normally, real invaders are mauled and sent packing within minutes.

But in addition to visual cues, paper wasps use chemical cues -- or scent -- on their exoskeletons as identification. Because of the chemical cues, nest mates were able to distinguish between friends and intruders and then to associate the painted markings with rank. With this recognition, aggression declined.

"Basically the wasp sees a painted wasp with altered markings and thinks, 'She smells right, so she must be a nest mate, but if I don't recognize her, is she a threat to my rank?' So the wasp is aggressive," says Tibbetts. "Whenever the nest mate then sees the altered wasp, she will know who it is and think, 'No need to worry, it is just Susie over there laying an egg.' Hence individual recognition."

The wasps' eyesight impressed Tibbetts. "The use of visual cues for the wasps is somewhat surprising, as insects are often thought to have relatively poor vision," says Tibbetts. "Although no one knows exactly how well they see, their vision is likely similar to honeybees."