Farmer Adam Macrae says it felt like thousands of mice descended on his Coonamble property almost overnight a few months back and since then he has spent tens of thousands trying to fight them. But they're still there.

Intensive baiting programmes have so far had little success against the infestation, and locals are hoping for heavy rain to drown the mice in their burrows.

Exterminators are fielding more calls about rodent activity. Rat-related calls are up 20 percent from last year; include mice and calls are up 57 percent.

Her right hand protected by an old plastic bag, Donna Devlin carefully reaches into a shallow sewer basin in her driveway, and drags out a dead rat the size of her forearm. It's the latest casualty in a war that Devlin and her neighbours say they've been fighting, on and off, for two decades.