London, Feb 19 (IANS): Ants do not go outside to do their business when nature calls and may use the corners of their nests as 'toilets', a study shows.

"For ants, which like us live in very dense communities, sanitation is a big problem," said lead researcher Tomer Czaczkes from the University of Regensburg, Germany.

Little research has been done on ant sanitary behaviour, 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 colouring and observed the nests for the colorful feces.

The researchers found that one or two corners of each nest started to fill with feces that was the same colour 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 did not just put their toilets anywhere -- almost all the ants placed their toilets in the corners.

"Ants normally keep a very clean nest, and usually throw out dangerous rubbish, like food remains and corpses," Czaczkes added.

The researchers are still not quite sure why the ants do this, but suggest that perhaps the piled-up waste might be useful.

The study appeared in the journal PLOS ONE.