2026 mouse plague devastates WA, SA farms and towns
Consensus Summary
A severe mouse plague has overwhelmed southern and Western Australia since early 2026, with plague-level infestations exceeding 8,000 mice per hectare in some WA farming regions. The outbreak follows record grain harvests and summer rains, creating ideal breeding conditions. Mice have spread from farms into towns like Morawa and Northampton, infesting homes, businesses, and public spaces, prompting health alerts and economic losses. Farmers and residents report mice damaging crops, machinery, and property, with some abandoning homes due to the relentless infestation. In response, authorities approved emergency permits for double-strength zinc phosphide bait, which requires only one poisoned grain to kill a mouse, though experts warn it is not a complete solution. The plague mirrors the 2021 NSW/Queensland outbreak, causing significant psychological and financial strain, with estimates suggesting potential billion-dollar crop losses if unchecked.
✓ Verified by 2+ sources
Key details reported by multiple sources:
- A mouse plague is affecting southern and Western Australia, with plague levels defined as over 800 mice per hectare by CSIRO.
- In some areas of Western Australia, mouse numbers have reached up to 8,000 mice per hectare, with 40 burrows per 100 square metres (4,000 burrows per hectare) and an estimated 2 mice per burrow.
- The plague zones include the west coast around Geraldton, Merredin, Esperance region in WA, and Adelaide Plains and Yorke Peninsula in South Australia.
- The Australian Pesticides and Veterinary Medicines Authority (APVMA) issued an emergency permit for double-strength mouse bait (ZP50) to farmers in May 2026.
- The double-strength bait contains 50 grams per kilogram of zinc phosphide, requiring only one poisoned grain to kill a mouse, compared to the standard 25g/kg bait.
- Mice have spread from farmland into towns like Morawa and Northampton, infesting homes, businesses, and public buildings, causing significant economic and psychological distress.
- The WA Health Department issued a public health alert urging increased hygiene and care due to the risk of disease from mice.
- CSIRO mouse plague expert Steve Henry compared the current WA outbreak to the 2021 NSW/Queensland plague, which caused millions in damage.
- Mice are damaging crops, farm machinery, and infrastructure, with reports of mice chewing wiring, hoses, and nesting in beds, ovens, and appliances.
- The plague began after a record grain harvest in WA, with abundant food and summer rain creating ideal breeding conditions.
Points of Difference
Details reported by only one source:
- A rugby/soccer field (2/3 hectare) would contain ~5,440 mice at plague levels.
- A suburban block (~400 sqm) could host ~10 mice in a 3m x 4m bedroom.
- The 2021 NSW/Queensland plague caused millions in damage and mental distress, with WA now facing similar conditions.
- Farmers report mice biting toes and nesting in beds after holidays.
- The 1993 SA/Victoria plague caused $96 million in damage.
- Historically, WA had fewer mouse issues than eastern states, but recent years show increasing outbreaks.
- Morawa Shire President Karen Chappel described the situation as 'horrid,' with residents constantly cleaning dead mice and dealing with odors.
- A Morawa grocery store owner reported losing tens of thousands in stock due to mice.
- Scientists warned of a $1 billion threat to WA grain crops if urgent action wasn’t taken in April 2026.
- A Morawa roadhouse operator said it takes an extra hour daily to clean the store and expressed hope for cold weather to reduce mouse numbers.
Where the reporting differs
Details that conflict, or appear in only some outlets:
- Article 1 (ABC) states the 2021 NSW/Queensland plague caused 'millions' in damage, while Article 3 (NEWSCOMAU) specifies $660 million but notes psychological impacts were not included.
- Article 1 (ABC) mentions mice in Adelaide CBD via FeralScan, but no other source confirms this specific urban spread.
Source Articles
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A mouse plague is invading farms and homes in southern and Western Australia. But what does that really look like?
A mouse plague has broken out, here's what you need to know
Mice in their millions are eating grain crops, destroying food, and invading houses. Here's how it all started.
‘Horrid:’ Mouse plague reaches epic proportions
An entire Aussie town is under siege from an animal plague of “horrid” proportions – sparking misery and psychological torment for residents.