NEW BLOG POST - Fly Control

Tuesday, June 18, 2024

Don’t be a fly on the wall, get on top of fly control today

We are now heading into that time of year where flies are rapidly multiplying. They can cause a multitude of issues affecting cattle, sheep and camelids. There are over 7,000 species of fly in the UK however, only 20 of these affect livestock. One female fly can lay hundreds of eggs across their life span. Flies deposit their eggs into rotting organic material, manure and leftover food. Eggs hatch into larvae, commonly called maggots, feed incessantly on organic matter.

Not only are flies a nuisance, but they can also cause some serious clinical disease in livestock. Sheep can be affected by flystrike that can be fatal. Flystrike is more common in warm wet conditions. Flies lay their eggs within the wool which then hatch into larvae within as little as 12 hours. During optimum conditions, these mature into third stage maggots within 3 days. These maggots feed on the skin causing large open wounds that are susceptible to secondary bacterial infections. They also release toxins that can cause the sheep to enter shock and die. Camelids are also susceptible to flystrike. Flystrike can also affect feet if footrot is present so prompt treatment of lame animals is essential. To aid with early detection of flystrike and therefore better outcomes of treatment, livestock should be checked twice a day over the high risk period.

In cattle, flies are a key vector in transmitting Moraxella bovis. This is the bacteria that causes infectious bovine keratoconjunctivitis or more commonly known as New Forest Eye. Clinical signs of this disease include discharge that can be pus and cause matting of the hair, squinting, pain, corneal ulceration and conjunctivitis. To treat New Forest Eye, antibiotics are needed which can be either a topical ointment or an injection. A crucial part of control of New Forest Eye is trying to reduce transmission from cow to cow via fly control.  


Fly control

For sheep, using Clik or Crovect would be best. Determining which product is most suitable for your flock depends on a number of factors, duration of product, weight of animals and withdrawal periods. Another difference is only Crovect is licensed for treatment of flystrike whereas both can be used for prevention. Whatever product you chose, ensuring the product is applied correctly  as per label instructions is essential for efficacy. For cattle, the most common products are spot on applications such as Spotinor. These are applied by a spot on the midline of the shoulders. They last for varying lengths of time so consider this when selecting your product.

Cattle fly tags can also be used to provide season long fly control against nuisance and biting flies. These are suitable for all ages with no meat or milk withdrawals. They are impregnated with cypermethrin and provide protection from flies for 5 months. 1 or 2 tags can be used depending on the level of the fly population. Using these tags can be useful as it reduces the amount of handling needed through summer compared to using traditional pour on fly products.

Parasitic wasps are a recent innovation that are dispersed around the farm targeting areas where flies are breeding such as along walls and under feeders. They are spread as wasp pupae which then hatch out. These wasps then reproduce by laying their ages inside the pupae of nuisance flies. The wasp pupae feed off the contents of the nuisance fly pupae preventing them from hatching. This would be a more sustainable method of fly control.

Fly traps can be used around housing to reduce fly populations. These only kill adult flies so other methods are likely to be required to further reduce populations by targeting earlier stages in their life cycle. Another important factor in fly control is prompt disposal of fallen stock is important. Flies will be attracted to these so increase your risk of flies being around.

In summary, controlling flies is not a simple process and to control flies effectively, a multifaceted approach must be taken.