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Farming 101 - Fight Back Against Fly Strike

Tim Ryman |

Flies can create many problems for farm owners, but it is the sheep farms that stand at maximum risk of falling prey to a fly strike. Flies have the most disastrous impact on sheep and can cause extensive damage to the farming industry too, so farmers need to go to whatever lengths possible to avoid a fly strike infestation.

This blog will cover several aspects relating to fly strike, such as the factors that increase the susceptibility of sheep and what preventive measures can be taken to minimise the risk.

What is Fly Strike?

Fly strike, also known as Blowfly strike, is said to occur when sheep get infected with a skin disease. Each year, it affects nearly 80% of sheep farms in the UK.

The possibility and occurrence of a fly strike is governed by the climatic conditions of a region. Regions with a moderate climate are the most affected – so countries such as the UK, Ireland, Australia, New Zealand and South Africa are all badly affected each year.

It is during the hottest months that blowflies reach the peak of their population and also their assault on sheep. Rainy weather only encourages blowflies and as inhabitants of the UK, the constant rain throughout the year can become a nightmare for numerous reasons, including flystrike.

Types of Blowfly Strike

On a sheep’s body there are certain areas that are more prone than others to become a host to blowflies. Following are the two types of most commonly occurring strikes:

Breech Strike

In this strike, the rear quarters of a sheep are more vulnerable due to the presence of wrinkles on the skin and dags on the wool.

Body Strike

The back and the flanks are the affected areas when a sheep has suffered from a body strike. This happens mainly due to lumpy wool and fleece rot.

Other types of strikes include the head or poll strike and pizzle strike – the latter occurring following wetting of the belly wool with urine.

How to Know When Sheep have been struck?

If you find that your animals seem to be stressed or annoyed for no good reason, it could be an indication that they have been attacked by flies. Besides changes in behaviour, they are also likely to experience fever, blood loss, inflammations, depression and reluctance to feed. It is important to treat the wounds as flystrike can claim the lives of the affected sheep, especially lambs.

Financial Loss due to Blowfly Strikes

According to a study conducted by Elanco in 2015:

Blowfly strikes are known to cause a financial loss of at least £2.2 million every year.

It has affected nearly 99% of sheep producers

One-fifth of the affected farmers have suffered losses to the extent of £500.

A lamb that has been struck causes a production loss of £10

Complete loss of lamb results in a loss of £80 and breeding their replacement ewe causes them a further loss of £200.

Also, handling a stricken animal requires an estimated labour cost of £10 and it takes 50p to get the animal treated.

Prevention of Blowfly Strikes


Before moving on to the preventive measures that a farm owner can take to cushion the impact of a blowfly strike, we should discuss which types of treatments are not effective.

Scientists have carried out extensive research on the subject of vaccination against blowflies but without much success. Scientists have found it difficult to understand the biology of the blowfly and until they figure out what is critical for the flies to grow, they cannot create an effective vaccination to use against them.

Blowfly traps are not very effective when it comes to reducing the incidence of fly strike. However, they can be used to monitor the population of blowflies.

Repellents are also known to have negligible effect on blowflies.

The best way to reduce the chances of a blowfly strike is to make the sheep less attractive for blowflies. Following are the measures that can be adopted to minimise the possibility of a fly strike:


Shearing suppresses the development of humid like conditions in the fleece that encourages the development of maggots. With the use of sheep shears, it is possible to maintain a dry environment which prohibits the number of eggs that can be laid and also the survival of larvae.


Removing the wool around the tail and between the rear legs reduces the amount of wool that is susceptible to infection. The lack of urine and feces on wool makes a sheep less attractive for flies, so having a consistent cleaning routine is important if you want to keep them at bay.

Buy our sheep shears today to keep your precious sheep safe during the summers. A small amount now will save you a fortune in future. 

For help and advice on how to use our sheep clippers, check out this video. 

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