Unseasonably high rains and bumper harvests have resulted in an "apocalyptic" plague of mice tearing through regional New South Wales - with families and farmers alike saying they're struggling with one of the worst rodent outbreaks the state has seen.

Experts predict the number of mice per hectare in stricken areas of NSW could be as high as 1000 - with the biblical explosion of rodents leading to concerns the pests could chew through as much as $100 million worth of farmers' crops in the state.

For many farmers who have weathered savage drought, the plague is another blow after years of hardship.

Chloe Christian, whose family property at Milawa in northwest NSW is one of the state's largest cotton and wheat producers, said there was "no end in sight" to the outbreak threatening their crops and even their homes.

"I don't think I've seen a plague that has hit in huge waves like this before, I've seen a few, but none this apocalyptic," she told The Daily Telegraph.

"This is some of the first crops in years for many farmers … and now we are being affected by the plague that can cost them (the entire crop)."

For many on the land, the impact isn't just being felt on the crops - but also on their homes and possessions, with the family forced to urgently repair their car after waves of mice chewed through the seats, carpets and wiring.

"(We've had) all the signs of the world gone mad - drought, disease and now plague," she said.

CSIRO research officer Steve Henry said it was impossible to quantify the number of rodents tearing across the state, but added this year's plague was "really bad" - with farmers at risk of losing their summer crops.

"People in the cities are seeing is a microcosm of what people in the country are dealing with," he said.

Rain and the bumper harvest of grain that came with it over the summer is the main reason for the population boom, according to University of Sydney Professor Peter Backs.

One night worth of trapped mice at Milawa, about 20 kilometres from Warren, where residents say they are
One night worth of trapped mice at Milawa, about 20 kilometres from Warren, where residents say they are "suffering with no end in sight here" due to the plague. Picture: Supplied


Prof Backs, a conservation expert focusing on pest control, said that while mice "don't really plague in cities like they do in our major grain growing areas", city-slickers might still experience growing numbers of mice because "rain feeds rodents".

Around 500km to the south of Chloe Christian's farm, corn and rice farmer Glen Andreazza said he was facing frighteningly similar problems.

The farmer, from Willbriggie near Griffith, said mice were hammering both of his crops despite repeated bait drops aimed at cutting the pest's numbers down.

"It could be one of the worst I've ever seen," he said of the plague.

"You drive down to the field in the night and you see them running everywhere."


Originally published as Apocalyptic: 'biblical' rodent explosion plagues NSW