The fireant is an insect that bites and stings but the bite itself is not what inflicts pain. This social insect will (when disturbed or when its colony is disturbed) emits powerful pheromones that attract and alarm other members of the colony. These pheromones call the colony members to the attack. Once the fireant locates and contacts what it perceives to be its enemy, it first bites its victim or attacker. This bite is not intended for use as pain inflicting device but rather as a means to hold on so that it can use its stinger. The fireants that cover your feet, ankles and legs after you step on their mound are all female ants. The stinger is actually a modified ovipositor which (by definition) is an egg laying apparatus of a female insect.
After attaching itself to your skin with its teeth, the fireant can better deliver its painful sting. The ant swivels around as it holds on, delivering multiple stings in a circular pattern. The fireant stinger is not barbed (as is the stinger of the honey bee) and does not remain impaled in the skin. This allows each fireant to deliver many stings without causing its own death. (Insects with a barbed stinger can only sting one time, as the barbs cause the stinger to remain in its victim, also causing death in the insect delivering the sting.)
Another difference between the sting of the fireant and the sting of other insects lies in the substance injected by its stinger. Wasps, bees, yellow jackets and other stinging insects deliver certain proteins into our skin that cause the painful, burning sensation associated with their stings. The fireant sting, however, does not contain this type of material. The venom of fireants contains alkaloids combined with relatively small amounts of protein. This venom is very effective for killing insects and also kills certain fungi and bacteria.
The sting of a single fireant is not nearly as painful as a single sting from a wasp or centipede. The pain and danger lies in the multiple stings delivered by a single ant and (most important) the fact that fireants rarely attack alone. Their powerful pheromones tell their colony members that help is needed. The real pain of fireants comes from the combination of hundreds of angry insects - and each one stings numerous times.

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Bites and Stings