fire ant sting, a potentially lethal venomous injection of piperidine alkaloids by a fire ant. The ant attaches itself to the skin with its mandibles and injects venom through a stinger in the posterior part of its abdomen. The ant injects repeatedly as it rotates its body around the attachment site. All victims experience a local wheal and flare reaction that lasts up to an hour, followed by formation of a sterile pustule. The pustule sloughs off after about 48 hours but is followed by itching that may last for days. Fire ant stings are a common cause of anaphylaxis in the southern United States.