Hand-colored scanning electron micrograph of the stinger of an ant (Paltotyreus tarsatus), by Martin Oeggerli.
The stink-ant has volatile material in the venom gland, which includes bitter-tasting cyclic dipeptides (Morgan et al., 2003). Stings are used to forage and for self-defense. Sting pheromones are set free to alarm co-workers upon a sting. Forage workers are also spraying chemical trails in order to recruit co-workers.
In general, the stinger is believed to be a rudiment in ants, which have evolved from early solitary hunting hymenopterans. Modern species with a conserved stinger belong to different sub-families, while their closest relatives may have reduced this ancient weapon (especially the more herbivorous species).
The bullet-ant (Paraponera clavata) has the most painful sting among insects. According to the Schmidt sting pain index, it is given a “4+” rating, above the tarantula hawk wasp, and according to some victims, equal to being shot, hence the name of the insect. It is described as causing “waves of burning, throbbing, all-consuming pain that continues unabated for up to 24 hours”. Poneratoxin, a paralyzing neurotoxic peptide isolated from the venom, affects voltage-dependent sodium ion channels and blocks the synaptic transmission in the central nervous system. It is being investigated for possible medical applications.
The Sateré-Mawé people of Brazil use intentional bullet ant stings as part of their initiation rites to become warriors. The ants are first rendered unconscious by submerging them in a natural sedative, and then hundreds of them are woven into gloves made of leaves (which resembles a large oven mitt), stingers facing inward. When the ants regain consciousness, a boy slips the gloves onto his hands. The goal of this initiation rite is to keep the glove on for a full 5 minutes. When finished, the boy’s hand and part of his arm are temporarily paralyzed because of the ant venom, and he may shake uncontrollably for days.