Most species of ants are considered ‘nuisance pests,’ meaning that they don’t pose a significant threat to health or property, but are an annoyance when found indoors. In fact, ants are the number one nuisance pest in the United States.
Some species of ants, however, can pose threats to health and property. Carpenter ants, for example, excavate wood in order to build their nests, which can cause extensive damage to a structure. Fire ants, on the other hand, sting when threatened, resulting in painful welts that can be dangerous to allergic persons. These species should always be handled by a professional.
Regardless of the species all ants can contaminate food sources and small infestations can grow quickly, so any sign of an infestation should be dealt with promptly.