Green’s Dictionary of Slang

(W.I./UK black) to live as a parasite.

1956		S. Selvon Lonely Londoners 32: I new in this country and I don’t want to start antsing on the State unless I have to.
1988		S. Selvon Eldorado West One 18: Damn reprobates and scoundrels, the lot of them, always antsing on a man.