Sanitary behavior in queenright and queenless ant colonies

•Most queenless and queenright colony fragments of the ant Temnothorax crassispinus form latrine patches inside the nest.•Latrine formation in the nest is independent of queen presence and there is no evidence for an effect of genetic variation.•Workers from queenless colonies defecate more frequently outside the nest.•Latrine formation affects mould growth inside the nest.•Colonies do not avoid mouldy nests, hence microbiota growth seems to be no threat for ant colonies. Waste disposal is important for maintaining the health of animal societies. Adults and off ;spring produce large amounts of waste and feces that could contain pathogens or toxins and may need to be stored away from the young or adult individuals. In social insects, the worker caste is responsible for nest maintenance, including sanitary behavior, and waste disposal strategies vary between species. However, individual task allocation is generally affected by queen presence and worker efficiency often decreases in the absence of a queen. Here we show that most (74%) colonies of the cavity-dwelling ant Temnothorax crassispinus construct up to two localized indoor ‘latrines’, which are used for defecation and only very rarely also as waste dumps. Restriction of defecation to designated areas affects the growth of mold inside the nest. Defecation strategies of colonies are furthermore affected by queen presence, with workers from queenless nests more frequently defecating outside the nest and forming latrines. As colonies do not actively avoid moldy nests, mold seems to not necessarily be a threat to the colony. While solid waste management has been more extensively studied in social insects, this study contributes a rare insight into the organization of non-easily transportable fecal waste.