Weird & Wild

Ants Maintain 'Toilets' in Their Nests, First-Ever Study Shows

Designated bathrooms may keep the colony healthy or feed its young.
Enlarge

Black garden ants (pictured, an individual in Germany) accumulate their waste in a designated area of their nests.


The first in-depth look at ant bathroom habits has found that some of the insects maintain "toilets" in their intricate underground colonies.

Scientists studying black garden ants discovered that the bugs pile their waste in dedicated corners of their nests. This makes sense: With thousands of ants confined to such a small space, organization is key. (Related: "To Stay Alive, Ants Dump Their Dead.")

What's more, feces can foster bacteria, transmit diseases, and generally put the colony in danger.

"Ants are indeed tidy creatures, but we must be careful not to anthropomorphize," cautioned study leader Tomer Czaczkes, a postdoctoral research fellow at Germany's University of Regensburg.

"They are not tidy because it brings them satisfaction, but rather because there must be a selective advantage to being so."

When Nature Calls

Czaczkes and his co-authors studied 21 small, lab-grown colonies of black garden ants (Lasius niger), a species found in large parts of the world.

The team selectively fed the insects a sugar solution colored with food dye. Some ants got red, while others got blue.

When a blue ant defecated, its feces was also blue. This showed the scientists where the ants deposited their waste—technically called "frass." (See "Surprising Ant 'Mixing Bowl' Found in Manhattan.")

After two months, a pattern emerged. In both the blue-dyed and the red-dyed ants' nests, distinct patches of color started accumulating in the nests—predominantly in the corners. Clearly, the ants consolidated their frass in "toilet" areas, instead of just letting it lie about. But why?

"If I were forced to choose, I would say that the mostly inactive ants in the nest simply do not want to leave the nest, as this would be dangerous," said Czaczkes. So instead they keep their living space spic-and-span.

In the paper, published February 18 in PLOS ONE, the authors noted that other social insects, such as honeybees and spider mites, go to great lengths to remove waste from their colonies.

Since black garden ants keep their waste inside, it may offer some unknown benefit to their society.

Toilet Talk

One such boon may be bonding time, noted Jae Choe, author of Secret Lives of Ants and president of South Korea's National Institute of Ecology.

For instance, naked mole rats—"the mammalian ants, if you will"—also make use of a common defecation place or toilet in their nest, said Choe. (See ant pictures in National Geographic magazine.)

Rat nestmates regularly visit this area and rub their bodies with the waste to coat themselves with pheromones that identify them as members of the group.

Some termites produce waste that has antimicrobial properties, which helps keep the colony healthy, said study leader Czaczkes—something he plans to research in the black garden ant.

It's also possible that the frass contains nutrients crucial for ant larvae, he added. In other words, one ant's frass may be another ant's treasure.

Ant Pictures From Your Shot

Follow Jason Bittel on Twitter and Facebook.

Comment on This Story