Green’s Dictionary of Slang

anty n.

[ants were frequently to be found in sugar]

(Aus.) sugar.

[Aus](con. WWI) A.G. Pretty Gloss. of Sl. [...] in the A.I.F. 1921–1924 (rev. t/s) n.p.: anty Sugar – so called on account of the frequency with which ants found their way into the sugar receptacles.