Mouse numbers have exploded to plague proportions across Western Australia's grain belt, with experts warning the outbreak is among the worst the state has seen.
CSIRO researcher Steve Henry says surveys in key cropping regions have found up to 4000 burrows per hectare, particularly around Northampton, north of Geraldton, and between Albany and Esperance near Ravensthorpe.
On conservative estimates of one mouse per burrow, that equates to about 4000 mice per hectare.
