Rats and mice are big problems in Australia, especially around the grain-growing regions in the south and in the east. Every few years, mouse population reaches gigantic proportions ravaging crops and gardens, and invading homes, hotels and restaurants. Even urban areas, such as Sydney, harbor a huge rodent population—between 500 million to a billion, according to one estimate. That’s one hundred rats for every resident at the lower end of the scale.

Men stand behind a mound of 500,000 mice caught in May 1917 at Lascelles, Victoria. Photo credit: F.G. England.

One of the largest infestations, or mouse plagues, occurred in 1917 when parts of Queensland and Victoria were literally overrun with mice. They damaged wheat, chewed boots, shoes, table-cloths, carpets, curtains, bed clothes and books. They bit babies in cradles, chewed through telephone and telegraph wires, nibbled at rubber stamps and parcels in railway stations. Mice leaped out every time drawers and cupboards were opened, startling the womenfolk of the house. Housewives routinely found dead mice floating in milk jugs, and even loaves of bread had to sliced warily as well-baked specimens were sometimes hidden in the interior.

Some mice managed to get inside the zoo and frightened the lions, while elephants screamed and trumpeted.

“The old order of things has been reversed and now the mice not only play when the cats are away, but actually play with the cats,” reported The Richmond River Herald and Northern Districts Advertiser. “[They] play all over them and around them, chew their little ears, and playfully nibble the tender tips of their tails. And the unfortunate cats have become so scared and disgusted that they now, whenever possible, roost in trees, and have taken to eating grass and noxious weeds.”

“The wheat at the Woomelang station is fast disappearing,” reported The Horsham Times. “Local farmers are unable to use their hay for horse feed, as the stacks are so badly infested with mice. The majority are burning the stacks and purchasing their chaff from other towns, where the fodder was not so seriously damaged by the pest.”

Wheat farmer Robert Wyllie with a night’s haul of mice near Minyip in Victoria's Wimmera district, circa 1917. Photo credit: boobookbacktracks.blogspot.com

Mice were caught and slain by tens of thousands every day. The biggest catch occurred at Lascelles, Victoria, where approximately 200,000 mice, weighing three tons, were caught on a single night. In another incident, two women in Rochester, Victoria, displaying extraordinary courage, jumped into a midst of scattering mice and slaughtered over a thousand in two hours. The incident was widely reported in several newspapers around Victoria under the heading “Women Massacre Mice”.

The plague was first noticed in February and March of 1917, and reached its peak between April and August. Before the outbreak was finally defeated, over 1,500 tons of mice—about a hundred million individuals—were killed.

The mouse plague of 1917 was significant but the most economically devastating one occurred in 1993 when the rodent caused damage worth AUD64 or AUD96 million, depending on who you ask. The pesky rodent destroyed thousands of hectares of crops, blighted piggeries and ravaged poultry farms. The following video shows how bad the situation was.

Photo credit: State Library of South Australia

Why Australia suffers routine outbreaks of mice plague is not fully understood. The invasive species is not even native to the continent. They arrived with the Europeans on the hold of ships probably in the late 18th century, and because it was an introduced species with no natural predators, they proliferated and their numbers grew wild. The most important factor that contributed to these outbreaks is likely weather. It has been shown that a good winter rainfall is necessary for an outbreak to take place, although it is not the only factor. By contrast, droughts are sufficient to prevent an outbreak. The availability of food is another likely contributor, but again, controlled experiments using laboratory population of mice showed no change in numbers when either water or food was added.

However, significant progress has been made in the past few decades, and researchers have developed a number of models that have been used to successfully predict mice outbreaks, allowing famers to take preemptive measures.

Over 2 tons of mice caught in three nights at Crystal Brook (S.A.). Photo credit: Cleland, J. B

Wheelbarrow overflowing with dead mice. Photo credit: Cleland, J. B