Methanoic acid (formic acid) is found in: 

Ants 

The correct answer is option 3. Ants.

Methanoic acid, also known as formic acid, is found in ants. Ants produce formic acid as a defense mechanism, and it is stored in their bodies and can be released when they feel threatened. Formic acid is responsible for the characteristic sting of some ant species and serves as a deterrent against predators. Therefore, the correct answer is Ants.