Which acid, named after ants, causes the sting of many ant bites?

Formic acid, also called methanoic acid, is the acid historically associated with the painful defenses and stings of many ants.

The name comes from Formica, the Latin word for ant and also the genus name of wood ants. Some wood ants can spray formic acid at predators or prey, while other ants deliver defensive chemicals through a sting. Formic acid is especially associated with ants in the subfamily Formicinae, although ant venom varies widely between species.

English naturalist John Ray described isolating the substance by distilling large numbers of ants in 1671. French chemist Joseph Gay-Lussac later synthesised it, and the compound eventually became important in industrial chemistry. Today, formic acid is also used in leather processing, textiles, chemical manufacture, and as a preservative in livestock feed.

A useful distinction is that not every painful ant bite or sting is caused mainly by formic acid. Fire-ant venom, for example, is dominated by alkaloid compounds. The quiz answer remains canonical because the acid's name and classic natural source are directly linked to ants.