When ants bite, they inject

Ant bites inject formic acid (chemical name: methanoic acid). A schoolbook example explicitly states that when an ant bites it injects an acidic liquid — formic acid — and that this can be neutralised with a base such as baking soda, explaining the burning sensation and common home remedy [1]. Educational lists of natural sources of common acids also identify ant stings as a source of methanoic (formic) acid, confirming the nomenclature equivalence [2]. Historical and chemical references further note that formic acid was first obtained from ants, and that the bites of some ants inject this simple carboxylic acid into the skin .

Sources

1. [1] Science-Class VII . NCERT(Revised ed 2025) > Chapter 2: Exploring Substances: Acidic, Basic, and Neutral > 2.3 Neutralisation in Daily Life > p. 18
2. [2] Science , class X (NCERT 2025 ed.) > Chapter 2: Acids, Bases and Salts > Table 2.3 Some naturally occurring acids > p. 28