Green’s Dictionary of Slang

mara n.

[‘A mara is an ant. The kind of ant that swarms together and then kills everything in front of them. One ant is easy to crush, but an army of ants is unstoppable. Conquer or die, ’manito, that’s us’ Winslow The Border (2019)]

(US gang) a gang member.

[US]D. Winslow Border [ebook] ‘You even know what a mara is?’ ‘A gangbanger’.