Fire ants are sensitive to vibration.
They grasp the skin with their jaws, arch the back and insert the rear end stinger into the flesh, injecting venom from the poison sac. They pivot their head and inflict seven or eight stings in a circular pattern. People with diabetes and others with circulatory disorders, including varicose veins and phlebitis, are especially at risk. You'll most likely develop itchy hives at the sting site which usually subside within an hour, followed by small blisters within four hours. Apply ice to the bite site.