Anting is when birds rub on their feathers insects, usually ants that secrete liquids containing chemicals such as formic acid, that can act as an insecticide, miticide, fungicide, or bactericide. It perhaps also can supplement the bird's own preen oil. Instead of ants, birds can also ant millipedes. Over 250 species of bird have been known to ant.
Some birds, including starlings, babblers, tanagers, and weavers, ant actively, that is, pecking up ants and rubbing them over their feathers. There are also passive anters, who just lie above anthills, such as the Eurasian Jay, crows and waxbills.
This behaviour was first described by E. Stresemann in German as einemsen in Ornith. Monatsber. XLIII. 138 in 1935. The Journal of Bombay Natural History Society XXXVIII described it in English in the following year and translated the term as "anting".