Researchers have long observed insect behavior, but the topic of sanitary habits has not been explored very well. For instance, what do ants do with their fecal matter?

A study sought out to understand sanitary habits in ants and found that nests have toilets inside. To be more precise, corners of nests are used as toilets.

Nests are extremely organized, with each ant assigned a specific role to fulfill day after day. While the ants carry out a routine, when they have to go, where do they?

In a study published in the journal PLOS ONE, Tomer Czaczkes and colleagues researched sanitary behavior in ants to determine whether or not the distinct brown patches they have previously observed in nests were fecal matter.

To find out, they gathered 21 small ant colonies and housed them in plaster nests in a foraging box. The ants were then fed colored sucrose solutions and different-colored protein sources.

The nests and foraging boxes were observed for two months, with pictures taken every week. After the observation period, the ants were removed from the nests. The researchers enlisted the aid of an uninformed observer to record the location of colored or darker patches present in the nests.

According to results, distinct, localized, colored patches were found in all 21 of the nests and they matched the color of the sugar solution given to a colony. Up to four patches have formed in every nest, with a total of 41 recorded. No other traces were found in the patches, indicating that the areas identified were solely used as toilets. Additionally, the ants didn't just happen to relieve themselves anywhere -- they all chose to place toilets in corners.

"This may be in order to avoid forcing ants to walk through the toilets, although the ants did not seem to avoid the toilets. Alternatively, corners may simply provide a practical feature to act as a nucleation point for stigmergic behavior," explained the researchers.

Stigmergic behavior involves the way in which an individual's actions toward the environment affect others, guiding them in what to do in the future.

The researchers, however, are not clear on why ants exhibit this kind of sanitary behavior.

"Some insects use feces for defense, as building materials, as manure for their crops, and as markings. Perhaps these toilets are also gardens for crops, or even stores for valuable nutrients," suggested Czaczkes.

The study received funding support from the Alexander von Humboldt Foundation. Other authors include Joachim Ruther and Jürgen Heinze.

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