Stinging ants are well known in practically every part of the inhabited world, and their poison is usually considered to be formic acid. The ants of the highest subfamily, the Formicinae, which includes most of the commonest ants in North America and Europe, have no functional sting, however, but do have a well developed poison vesicle containing formic acid. Many of these ants, when biting the skin, curve their abdomen forward to eject acid into the cut and thus give to the layman the impression of stinging. The ants of the lowest subfamily, the Ponerinae, do have a well developed sting, and the poison is so virulent that it would seem to be something more powerful than formic acid.
A widespread Ponerine ant in Central and South America is Paraponera clavata Fabr. The workers of this species are fully one inch long and the queen is still larger.