What is the distinguishing defensive chemistry associated with the Subfamily Formicinae, where *A. gracilipes* is placed?

Defense achieved by spraying formic acid

Ants belonging to the Subfamily Formicinae utilize a specific, common chemical defense mechanism: the expulsion or spraying of formic acid. This feature serves as a key biological marker that taxonomically separates them from other ant subfamilies, notably the Myrmicinae subfamily, which often rely on a physical stinger to inject defense mechanisms. While the formic acid used by *A. gracilipes* is noted as being relatively weak compared to some other ant species, the mechanism itself defines its placement within Formicinae.