CSIRO research officer Steve Henry said an “exceptional” cropping season and a good spring last year had seen mice begin to breed early, and continue breeding throughout summer and autumn.

The high yields of the crops had left plenty of stubble too, providing shelter for the rodents.

The CSIRO’s latest mouse monitoring report from March said mouse abundance was increasing across the state.

Mr Henry said mouse numbers had been higher than expected, but were “patchy”, with numbers high in some areas and low in others.

The Wimmera and Mallee regions are the most affected, but reports of mouse activity have been made in central Victoria.

Mr Henry said farmers were being advised that they might find mice in paddocks at a number that would cause economic damage: 200 mice or more per hectare

He advised farmers to check paddocks on foot for mouse activity and if they thought they had a problem, they probably did.

Farmers can check for mouse activity reports and make their own at the Mouse Alert website.

John Pay, from Go Pest Bendigo, said rodent activity had grown both in rural areas and within Bendigo itself.

To prevent mice setting up home in houses, Mr Pay advised people to clean up food scraps, look at where pets were fed because their food might attract pests, and be mindful of their environment in general.

He said those who found mice in their home could engage a pest controller or purchase their own bait, but warned these had to be used very carefully as they could prove fatal for pets if misused or used carelessly.

Mr Henry said the continued growth of mouse numbers would depend on the upcoming cropping season and the weather in winter, which would establish the base numbers from which mice would breed in spring.