Ants can sting or bite and use their venom to kill smaller creatures or to keep intruders away. Therefore, the best prevention is to avoid stepping or sitting on their nests. Two types of ants cause problems in Arizona; harvester ants and field ants. Harvester ants are large and red, dark brown or black in color. They can sting but the stingers are fairly blunt and the pain lasts four to six hours. Field ants are medium in size. After biting, they spray acid into the wound, causing short-lived pain