The phenomenon of ant nest (formicary) corrosion is reviewed. Current theones indicate that attack requires the simultaneous presence of moisture, oxygen and a corrodent, usually an organic acid, such as
formic acid. Morphological features are presented using several recent case studies as examples. This paper seeks to create more answers to this less appreciated phenomenon that causes premature corrosion
failure in copper tubes used typically for reiiigeration or air conditioning applications.