Green’s Dictionary of Slang

(Aus.) Catholics.

1993		Aus. Word Map 🌐 cattle tick. Catholic (rude school child insult of the 50s): All the cattle ticks have gone to mass.
2002		Pete’s Aussie Sl. Home Page 🌐 cattle ticks: Catholics.
2003		Bug (Aus.) Apr. 🌐 And [...] how about this ultra right-wing Cattle Tick archbishop they’ve plucked from Melbourne to head the whole shebang from Sydney?
2021		Betoota-isms 182: Cattle Tick [...] 1. A Catholic.