Cropping & Soil
26 November, 2025
History shows improved responses to mice plagues
READING through national newspaper archives to get a sense of what mouse plagues have been like throughout the Wimmera’s history can be an unsettling experience, even if the truth of some stories might’ve been exaggerated and led to some modern myths about the pest.
With significant events in 1899, 1917, 1932, 1947 – among too many other years to bother counting – such as stories of cats taking to flight from mice after gorging themselves and plagues supposedly only occurring in Australia and China (Argentina-2021, New Zealand-2020, and Pakistan-2019 would like a word) muddy the waters of research, but one thing is clear: responses from farmers in 2025 have at least gained from the intervening years of scientific understanding, medical knowledge and faster social communication.
What’s not so nice reading was, for example, multiple reports of horse mortality back then due to exposure to certain diseases contained in the hay and chaff mice have been feeding on:
It was possible that a contributory cause might be found in the decomposed bodies of the mice themselves, which were dying in large numbers.
The seriousness of the position could be gauged when it was realised that many men had to abandon the work of chaff-cutting, while the machine became bespattered with the blood of mice that were buried in the sheaves.
(The Horsham Times, Jun 12, 1917, p6)
Conditions likely to be ideal for mice
Recently-issued warnings from the Grains Research and Development Corporation and the CSIRO have made clear conditions have unfortunately been good for the rodents to feed well.
High burrow numbers of up to 125 per hectare have been detected at a site in the East Wimmera, and scientists say the combination of signs of high mouse activity and favourable weather conditions in the area makes for ongoing high breeding potential.
CSIRO research officer, Steve Henry, said among the common variables they look for – trapping success, proportion of pregnant females – there was an additional factor in the Wimmera region.
“One of the things that has transpired over the past few weeks is there has been some significantly windy weather through some parts of the cropping zone, and if barley crops are right at the point they're ready to be harvested, that wind will have caused some significant head loss in some areas,” he said.
“That will mean there's more food on the ground for mice than we would expect there normally to be.
“At the point when you’re seeing a few mice probably means they’re in numbers where you really need to be concerned so certainly continue to monitor and be prepared to take action if numbers continue to increase.”
He said the classic sign of a problem is mice running across roads in the evenings, and grain growers need to consider their own homes, too.
Plugging up holes, keeping pet food bowls clean and checking for contamination of water collection were just a few of the important steps to take.
Taking care with exposure to mice is also important, as they can transmit diseases such as leptospirosis, lymphocytic choriomeningitis virus (LCMV) infection, and gastrointestinal infections, including salmonellosis, campylobacteriosis, and cryptosporidiosis.
Diagnostic tools have improved with advances in medicine, providing faster and more accurate tests, enabling targeted treatment and tailored antibiotics or antiparasitics, and offering better support for complications.
However, the challenge of antimicrobial resistance remains a concern for bacterial diseases, so prevention is always considered the better path.
On the farm
Minyip farmer, Ryan Milgate, said, as farmers are wont to do, looking at history and seeing the current similarity from “some dry conditions, then going into a little bit better conditions” has helped to anticipate a rise in mice numbers.
He said apart from some “little hot spots” around Jung, where they always seem to have a few mice, they haven’t seen too much indication locally – yet.
But he was always on the lookout.
“They tend to do that a bit, they go through these cycles,” Mr Milgate said.
“In the last, say, 10 years, we've probably had three really bad ones.
“Coming to harvest, one of the key learnings is just making sure that we're not throwing a heap of grain out of the header and providing a lot of feed for the mice. That's number one.
“And then two, 10 years ago, we'd sow the crop, and then you come back a few days later and (realise) the mice are eating it.
“We've learned now to monitor a lot better, and we're generally a lot more aware of what's actually happening in the paddock before we have a problem.
“So rather than trying to chase our tail and bait mice that are eating us out of house and home and eating our crops – if we see numbers building up in the autumn, we're looking at strategic baiting.”
He added one tech development that has especially helped as a serendipitous innovation for being proactive in management, used for a somewhat different purpose than its original design.
“The other thing that's been a bit of a game changer just in the past couple of years is ... thermal rifle scopes,” Mr Milgate said.
“You can actually go out now ... and it's really easy to see mice in the dark, whereas in the past, you drive out with the ute and a torch – to see something that weighs 20 or 30 grammes in a bit of stubble can be nigh on impossible.”
He added networking was also critical.
“Farmers talk a lot, and they say, ‘Actually, you know, I saw a lot of mice in my paddock while I was harvesting my barley’ or something like that,” Mr Milgate said.
“Then it triggers a management reaction going forward.
“Social media’s made it easier – just people sharing what they're seeing out there.”
Research continues
Mr Henry said research into long-term solutions continues to be explored by the CSIRO.
"We're doing some research about understanding the role of background food in stubbles and just how it supports and sustains these populations through the stubble phase,” he said.
“The other thing we know about because of research we’ve done is that background food has a significant impact on the efficacy of the bait and it’s all about the probability of the mouse discovering the bait so the less background food you’ve got the better chance a mouse has of discovering that bait and getting a lethal dose, remembering that mice need to get two or three grains of the bait to get a lethal dose.”
This story has been compiled with support of the Australian Local News Resilience Project, an Australian Research Council project partnership between Deakin University and Griffith Universities and the ABC.