Formic acid is the simplest carboxylic acid, containing one carbon atom. Occurs naturally in various sources, including the venom of bee and ant stings, and is a useful reagent for organic synthesis. It is mainly used as a preservative and antibacterial agent in livestock feed.

Formic acid (from Latin formica "ant"), systematically named formic acid, is the simplest carboxylic acid with the formula HCOOH and the structure H−C(=O)−O−H. It is an important intermediate in chemical synthesis and occurs naturally, especially in certain ants. Esters, salts and anions derived from formic acid are called formates. Industrially, formic acid is produced from methanol.

In nature, formic acid is found in most ants and stingless bees of the genus Oxytrigona. [5] [6] Carpenter ants of the genus Formica can spray formic acid on their prey or defend their nests. Dark moth caterpillars (Cerura vinula) also spray it when threatened by predators. It is also found in the trichomes of stinging nettle (Urtica dioica). In addition to this, this acid is found in many fruits such as pineapple (0.21 mg per 100 g), apples (2 mg per 100 g) and kiwi (1 mg per 100 g), as well as many vegetables, namely onions (45 mg per 100 g), eggplant (1.34 mg per 100 g) and cucumber at very low concentrations (0.11 mg per 100 g) [7] Formic acid is a naturally occurring component in the atmosphere, mainly due to forest emissions.

Some alchemists and naturalists realized as early as the 15th century that anthills give off acidic vapors. The first person to describe the separation of this substance (by distilling large numbers of ants) was the English naturalist John Ray in 1671. [9][10] Ants secrete formic acid for both offensive and defensive purposes. Formic acid was first synthesized by French chemist Joseph Gay-Lussac from hydrocyanic acid. In 1855, another French chemist, Marcellin Berthelot, developed a method of synthesis from carbon monoxide similar to that used today.