Mice
The plague started in the spring of 2020 after the winter crop harvest, and at its peak the number of mice was estimated to have run into the billions. By mid 2021 the plague was estimated to have caused $100 million in damage to crops and grain stores alone. The government of New South Wales allocated A$50m (£27m; US$37m) for just one of a number of proposed antidotes. The problem was reduced to a manageable level but not until the end of 2021, and continued in 2022.