Ants may use the corners of their nest as 'toilets,' according to a study published February 18, 2015 in the open-access journal PLOS ONE by Tomer Czaczkes and colleagues from University of Regensburg, Germany.
Little research has been done on ant sanitary behavior, so the authors of this study conducted an experiment to determine whether distinct brown patches they observed forming in ants' nests were feces. They fed ants, living in white plaster nests, food dyed with either red or blue food coloring and observed the nests for the colorful feces.
They found that one or two corners of each nest started to fill with feces that was the same color as the food they were fed. The researchers found no other waste in these areas, suggesting that ants may use these areas as 'toilets.' They also discovered that the ants didn't just put their toilets anywhere—almost all the ants placed their toilets in the corners.
"For ants, which like us live in very dense communities, sanitation is a big problem," says Dr. Tomer Czaczkes, who led the study. "Ants normally keep a very clean nest, and usually throw out dangerous rubbish, like food remains and corpses."
The researchers are still not quite sure why the ants do this, but suggest that perhaps the piled-up waste might be useful. "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," added Dr. Czaczkes. Maybe, though, the ants just don't want to go outside to do their business.
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Czaczkes TJ, Heinze J, Ruther J (2015) Nest Etiquette—Where Ants Go When Nature Calls. PLoS ONE 10(2): e0118376. DOI: 10.1371/journal. pone.0118376