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Mulesing is the removal of strips of skin from around a lamb’s back end to prevent flystrike, a dangerous parasitic infection. The resulting scar tissue grows back smooth and bare, which makes the animal less vulnerable to blowflies. It is a practice almost entirely confined to Australia, and one that remains highly controversial.
At Garthenor Organic, we believe that understanding how wool is produced is part of making informed, sustainable choices. This post sets out what mulesing is, why it exists, why it is debated, and how you can be confident that every skein from Garthenor Organic is free from it.
(Content warning: this section describes animal health issues in some detail.)
Flystrike occurs when blowflies lay eggs in damp, dirty areas of a sheep’s fleece, particularly around the breech (the back end). Within hours, the eggs hatch into maggots, which burrow into the sheep’s skin and feed on its flesh.
The results are devastating. Flystrike causes painful wounds, infections, and, in severe cases, a slow death if untreated (Source: RSPCA Australia 2024). A struck sheep may decline within just a few days.
Merino sheep, especially those bred for heavy, wrinkled fleeces, are particularly at risk. The extra folds of skin trap moisture and dirt, creating the perfect conditions for blowflies.
The roots of the problem lie in breeding and biology. In the late 19th century, the Vermont Merino was introduced into Australia. These sheep had heavy skin folds, which increased fleece weight but also increased vulnerability to flystrike. Around the same time, the blowfly (Lucilia cuprina) was accidentally introduced to Australia, spreading rapidly and compounding the problem (Source: Sneddon & Rollin, 2010, via UBC).
In 1929, J.H.W. Mules, a sheep breeder in South Australia, cut wrinkles from a ewe that was repeatedly struck by flystrike. When the wound healed, the smooth scar tissue resisted further attacks. Mules described the operation in a letter published in the Adelaide Advertiser in 1931. By 1940, the Joint Blowfly Committee recognised it as effective, and by 1947 the procedure was modified to include the sides of the tail to reduce both breech and tail strike. That is essentially the procedure still used today (Source: Beveridge, 1984; UBC).
Today, mulesing is concentrated in Australia. Around 70% of Merino sheep were still mulesed in 2019 (Source: WA Dept. of Primary Industries). The figure has since begun to decline as more non-mulesed wool reaches the market (Source: AWEX via Guardian 2024).
New Zealand banned mulesing in October 2018. The practice is not used in the UK, Europe, The Falkland Islands, or most of the rest of the world.
The reliance on mulesing stems from breeding choices. For decades, Australian Merinos were selected for wrinkled skin that carried more fleece. More wrinkles meant more wool - but also much greater susceptibility to flystrike.
Mulesing sits at the intersection of two welfare issues: the severe risk of flystrike and the pain caused by the procedure itself.
Arguments in favour stress that mulesing prevents enormous losses from flystrike. Industry groups argue that until replacements are available, it remains the most reliable way to prevent breech strike (Source: AWI, 2008). Research suggests it reduces risk by up to 13 times (Source: Fisher et al., Animal Welfare 2013).
Arguments against focus on animal suffering. Mulesing causes long-lasting pain, reduced feeding, hunched posture, and avoidance behaviour. Even when pain relief is used, discomfort remains. Uptake of analgesia has improved dramatically - from none in 2006 to 86% of growers by 2020 (Source: Woolmark 2021) - but this only lessens, not removes, the impact.
The market has accelerated change. Since the early 2000s, campaigns by animal welfare groups and international retailers pressured the industry to move away from mulesing. Today, non-mulesed wool attracts price premiums at auction, with 5% annual growth in non-mulesed bales (Source: AWEX via Guardian 2024).
There is no single solution, but several alternatives are in practice or development:
Most producers now combine management with genetic selection, gradually reducing reliance on mulesing.
For knitters, the most straightforward way to avoid mulesed wool is to look for credible certifications:
Choosing yarns with these certifications - or asking companies directly - is the best way to ensure the wool you’re buying is mulesing-free.
At Garthenor Organic, our position is categorical. We have never used wool from mulesed sheep - and we never will.
All of our yarns are certified to GOTS, which explicitly bans mulesed wool. Even without that rule, we would not consider it. Our long-standing relationships with British woolgrowers give us full traceability, and we can say with certainty that mulesing has never formed part of our story.
We also believe mulesing should end. While we recognise the challenges of flystrike, we know there are better ways forward through breeding, careful flock management, and innovation.
Mulesing was developed to address a genuine welfare risk, but it has itself become one of the most controversial practices in sheep farming. While it remains common in Australia, the global industry is shifting towards alternatives - pushed by science, welfare standards, and consumer demand.
For knitters, the choice is simple: look for yarns that are certified mulesing-free. Every skein from Garthenor Organic is traceable, organic, and categorically free from mulesed wool.
Thank you for such an informative piece of writing. Very interesting read.
Brad Lichtenstein
September 03, 2025
Everything choice we make impacts the health and wellbeing of not only humans, but also the more-than-human world. My choice of wool is larger than just my preferences and tastes. Thank you so much for sharing this information which empowers me to make conscious and thoughtful decisions.