Forget breeding like rabbits, it's mice that are breeding in plague proportions.

They start breeding at just six weeks of age and can give birth to a litter of up to 10 offspring every 20 days.

And on top of that feat, a mouse can fall pregnant immediately after giving birth.

Their prolific breeding has scientists, including CSIRO research officer and mouse guru Steve Henry, concerned.

"It's pretty scary how quickly they can breed up," he said.

"They're breeding machines [and] in just one season, a pair of mice can give rise to 500 offspring."

CSIRO researcher Steve Henry weighs a mouse. ( ABC News: Alice Kenney )

Mr Henry said a mice plague was looming for farmers this season and they needed to act now to stymie breeding.

He said mouse numbers in southern New South Wales, Victoria, and South Australian were currently higher than they would normally be at this time of year.

"It's quite concerning," Mr Henry said.

"If they continue to breed from now through to sowing, they could cause significant damage once crops are sown in autumn."

Perfect breeding conditions

A combination of ample food and shelter has led to perfect breeding conditions for mice.

Huge crops were harvested in 2016 and plenty of grain was left in paddocks as a result.

Mice are breeding machines. ( ABC Rural: Annabelle Homer )

"There was a lot of food left in the cropping systems so a lot of mice got breeding and pushed the number really high," Mr Henry said.

Those mouse numbers remained high through the winter and into the 2017 harvest.

"The 2017 crop was a difficult one with a lot of frosts and it was a wet harvest, so farmers were pushing to get crops off and that led to a fair bit of grain being left on the ground," he said.

The continued supply of food means the breeding cycle continued this summer.

Staying ahead of the pack

Mr Henry is calling on growers to implement monitoring and baiting programs well ahead of sowing to prevent a major outbreak.

"It's really important for farmers to get out of their vehicles and go for a walk in the paddock to find out what is going on with mice numbers," he said.

"Heavy stubbles in paddocks can mask the sign of mouse activity and farmers often don't realise how bad their mice numbers are until they start sowing their crops."

This little guy's not going anywhere. ( ABC News: Harriet Tatham )

He said farmers should be inspecting their paddocks at least two months prior to sowing and implementing strategies to reduce the amount of food available.

"This can be done by spraying out weeds and using livestock to graze the paddocks," he said.

Mr Henry recommended farmers start baiting with zinc phosphate six weeks before sowing.

If mice numbers are still high at sowing, bait should be spread across the paddock straight off the back of a seeder.

"It is very important to get that bait out in the first 24 to 48 hours after sowing because that is when most of the damage happens," Mr Henry.

A numbers game

A mouse plague comes at a huge financial cost for farmers with research showing that when mice numbers hit 200 head per hectare, the economic costs start stacking up.

Mr Henry said when a mice plague strikes, it is usually about 800 mice per hectare.

A mouse plague can cause havoc on farms. ( CSIRO )

"People in the towns complain if they have one mouse in their house, but when plagues hit rural areas, people have hundreds of mice in their houses," he said.

Some farmers have reported spending more than $100,000 on mouse control last year.

"Last season some growers had to re-sow paddocks three times and apply bait six times to try and control mice on their farms," Mr Henry said.

Here today, gone tomorrow

Farmers hoping for a biocontrol method similar to the strain of calicivirus K5 released last year to combat booming feral rabbit numbers still have a wait ahead, according to Mr Henry.

"We do need to keeping looking for alternatives to spreading toxins but at the moment, biocontrol for mice is a significant distance away," he said.

For now, he said the best way to keep mice at bay is to deplete their food source.

"Historically, mouse numbers crash away very dramatically without food," Mr Henry said.

"When mice are running around at such a high density, disease becomes prevalent.

"That, combined with a food shortage, leads to them eating each other."