Fly Strike
Why This Page Matters
Fly strike can be a major headache for lifestyle farmers.
If you’re not informed, it can quickly become a problem for your flock in the warmer months. There are also many misconceptions about the safety of chemical treatments, which can lead to poor decisions.
That’s why I urge you to take the time to read this page carefully. Understanding fly strike and correct preventative and treatment measures can make all the difference in protecting your flock from fly strike.
Understanding Fly Strike
Fly strike is a serious condition where blowflies lay eggs on sheep, leading to maggots that can cause severe damage and death if left untreated.
Preventative measures are essential to protect your flock from fly strike.
Fly Strike
Prevention and Safe Handling
Shearing: Your Best Defense
Regular shearing is the most effective way to prevent fly strike. By removing the wool, you eliminate the environment that allows fly eggs and maggots to thrive. This also improves airflow and sunlight exposure, both of which are natural deterrents to infestation.
- Protection Period: Shearing offers up to 6 weeks of protection against fly strike.
- More Frequent Shearing: In particularly bad seasons, consider shearing twice during the warmer months to enhance protection. This is what I do with my own sheep and I avoid any issues with fly strike.
When comparing costs as a lifestyle farmer, there isn't much difference in price if you compare a second shear with the cost of applying a pour-on fly strike preventative.
Warning Against Hazardous Chemicals
It's important to note that not all pour-on treatments are safe. In fact almost none are safe. Many contain toxic chemicals that pose significant health risks to shearers and anyone who handles treated sheep.
Maggo and Zapp Encore:
These products are extremely hazardous, with Maggo being classified as a human carcinogen. It can cause organ damage and cancer with repeated exposure.
The chemical lingers on the sheep's skin and wool, contaminating anyone who handles the sheep, including shearing equipment and clothing, and can even affect your household through the washing machine.
I will not shear sheep treated with Maggo. And I will not shear sheep treated with any other pour on within the last 2 months of application.
Considering Zapp Encore is commonly used in the Auckland and Northland regions, it is extremely important to note: It is considerably more toxic than most users realise and should be used with extreme care.
- Zapp requires a meat withholding period of 56 days. This is particularly concerning if you farm sheep for the freezer.
A better alternative to using any pour-on is shearing your sheep more regularly.
What is the Safest Pour-On Fly Strike Preventative
While shearing is highly effective, some flock owners may also consider pour-on treatments. It's crucial to use products that are safe for both the sheep and the humans handling them.
- Extinosad: This is one of the safest pour-on options available. It’s approved for use on organic farms and has no withholding period for meat or wool. The active ingredient, spinosad, is derived from naturally occurring soil bacteria.
Protection Period: Up to 6 weeks.
What I use for Clients That Want a Pour-On Applied
For those that request a fly stirke prevenative pour-on seeking a longer-lasting option, Clik Extra is highly effective, providing protection for 14 to 26 weeks. However, when the flies are at their worst I would only count on that protection lasting for up to 14 weeks.
Although Clik Extra contains chemicals, it’s safer compared to other treatments that contain nasty organophosphate chemicals.
- Protection Period: 14 to 26 weeks.
- Withholding Periods: 21 days for meat, 2 months for wool.
A better alternative to using any pour-on is shearing your sheep more regularly.
Can Sheep Be Shorn After Applying a Pour-On
No.
Sheep should not be shorn shortly after applying a pour-on treatment. This includes if the sheep has been spot treated. If a vet tells you they are fine to shear after a spot treatment with a chemical, they are putting others health at risk. Best practice is to shear the sheep completely first.
The chemical lingers on the sheep's skin and wool, contaminating anyone who handles the sheep, including shearing equipment and clothing, and can even affect your household through the washing machine.
Each product has a minimum wool withholding period of 2 months or longer.
Handling sheep within this timeframe poses significant health risks, so it’s essential to plan your flock management accordingly.
Other Ways to Reduce the Chances of Fly Strike
- Grazing sheep in paddocks away from dense bush
- Grazing sheep in paddocks exposed to the wind
- Crutch your sheep if they get any dags around the breech
- Shear your sheep twice over the warmer months of the year
- Rotational grazing to minimise build-up of faecal matter (don’t overgraze)
- Monitor your flock regularly (daily after rainfall in humid conditions)
- Remove any wool around an area you suspect to be affected at first site (get yourself a set of hand shears or clippers to do this quickly and easily)
- Flies like to lay their eggs on decaying matter - keeping your sheep at their optimal health and hygiene reduces the risk of fly strike greatly.
Fly Strike
Treatment
How to Treat a Fly Struck Sheep
- Step 1: Immediately seperate the affected sheep from the flock.
(Fly strike attracts more flies, increasing the chances of other sheep getting struck). - Step 2: Remove all of the wool from the affected area so that sunlight can get in to the skin.
- Step 3: If you are unable to remove the wool, apply a Salt Water Solution (pool salt/non-iodised salt) to the affected area. 1/4 cup of salt to 1 litre of water.
- Step 4: Organise a shearer to come and do a full shear.
- Step 5: Once the sheep is fully shorn and if needed apply Stockholm Tar.
In most cases just shearing the sheep is effective, if you have caught the fly strike early enough, and the skin isn't broken.
Why Salt Water Works in the Short Term
- Dehydration of Maggots: Salt water works by creating a hypertonic environment, which draws moisture out of the maggots' bodies, leading to their dehydration and eventual death. This helps to eliminate the parasites without the need for harsh chemicals.
- Antiseptic Properties: Salt is a natural antiseptic. When dissolved in water, it creates a saline solution that helps to disinfect wounds by killing bacteria and other pathogens. This reduces the risk of secondary infections in the affected area.
- Wound Cleaning: The salt water helps to clean out debris, dead tissue, and maggot waste from the wound, promoting better healing conditions.
- Promotes Healing: Salt water helps to reduce swelling and inflammation around the affected area, aiding in the natural healing process of the skin and tissue.
Avoid Using Unnecessary Chemical Treatments
- If a chemical treatment has been used, even a spot treatment, the sheep cannot be shorn during the wool withholding period for health and safety reasons.
Flock Monitoring
Regularly inspect your flock during hot and humid seasons to catch any early signs of fly strike. Look for:
- Behavioural Changes: Sheep that separate from the flock or show signs of discomfort.
- Wet Patches of Wool: These may indicate the presence of fly eggs or larvae.
- Wounds or Lesions: Maggot activity can cause visible damage to the skin.
Early detection is key to preventing serious outcomes.
Learn More
For more information on preventing, identifying, and treating fly strike read The Complete Guide to Fly Strike in Sheep.
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