While some ants go out and forage for food, others simply hang around. Photo by Flickr/Bob Peterson

TUCSON, July 4 (UPI) -- Compartmentalized and regimented -- ant societies are a model of efficiency. But they're not perfect. Some ants are lazy.

When scientists at the University of Arizona noticed a significant percentage of social insects seem to be idle, they began to wonder: are they simply taking a break? Or are they deadbeats?


A new study suggests some Temnothorax rugatulus worker ants, a species native to the forests of the American West, are consistently lazy, making up a so-called idler class.

In studying several ant colonies in the lab, researchers at Arizona found nearly half of each colony's worker ants spent most of their time doing nothing at all. Researchers say they can't be sure whether the ants are slacking off or performing some sort of invisible task.

"Differences in circadian rhythms, or workers taking turns resting (i.e., working in shifts), cannot explain the observation that some workers are consistently inactive," researchers wrote in a new paper on the subject.

Scientists say it's possible the idle ants serve some sort of purpose in their laziness. Honeypot ants, or simply honey ants, feature a subsection of workers who hang from the ceiling of their home base and offer up a refreshing liquid drink from their abdomens to tired ants returning from the fields.

According to Tomer Czaczkes, an entomologist at Germany's University of Regensburg who wasn't involved in the study, the lazy half of the Temnothorax rugatulus colonies may simply be muscle.

"The apparently 'lazy' ants could also be acting as a reserve fighting force, since raiding, including raiding for slaves, is quite common amongst such ants," he told the NewScientist.

Lead researcher Daniel Charbonneau, an entomologist at Arizona, says he and his colleagues are currently testing a number of possibilities to find out whether the lazier ants are of a certain age. It's possible the ants are simply older specimens with slower metabolism, serving as food storage facilities.

"The thing is that these hypotheses aren't exclusive, so many things could be happening at the same time," says Charbonneau.

The new study was published this week in the journal Behavioral Ecology and Sociobiology.

"Our results underline the importance of inactivity as a behavioral state and the need for further studies on its evolution," the scientists concluded.