BOGAN GATE, Australia (AP) — At night, the floors of sheds vanish beneath carpets of scampering mice. Ceilings come alive with the sounds of scratching. One family blamed mice chewing electrical wires for their house burning down.

Vast tracts of land in Australia's New South Wales state are being threatened by a mouse plague that the state government describes as "absolutely unprecedented." Just how many millions of rodents have infested the agricultural plains across the state is guesswork.

"We're at a critical point now where if we don't significantly reduce the number of mice that are in pl...