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Cattle Fly Control and Treatment

Fly Control in Cattle 

David Jackson, BVetMed MRCVS Molecare Vet Services


The main months of fly activity in the UK are May to August, but as we all know, the seasons in this country can be very variable, so it is worth being prepared to treat right through to October.

With the mild winter, 2016 is anticipated to be a bad year for flies. Effective fly control has been shown to increase the feed conversion ratio in calves by up to 13% and milk production in cattle by up to 3%. Flies can also spread infections such as New Forest Eye and summer mastitis which contribute further to the production effects. Fly strike can occur in cattle, although less commonly than in sheep, for example on wounds from castration or dehorning.There are two areas to target when designing a fly control programme for your farm - the environment, and the animals themselves.




Environmental control:

There are many areas on farms which are ideal breeding grounds for flies:

• Dung heaps 

• Livestock bedding

• Slurry 

• Damp ground

A range of treatments are also available to reduce the environmental reservoir of flies on the farm. 

These include:

• Adulticidal and larvicidal sprays

• Fly lamps and fly traps for buildings

• Citronella based repellents

Don’t get caught out by flies this summer, speak to your vet and Mole Valley SQPs today to get a fly control strategy in place for your farm.



Flies (including midges) and lice are two of the most common ectoparasites which cause serious problems for cattle farmers.

STABLE FLY (Stomoxys calcitrans) can reduce milk yield by up to 20% and reduce weight gain in beef cattle by 50-300g per day.

FACE FLY (Musca autumnalis) has been linked with the transmission of a bacteria - moraxella bovis - which is associated with pink eye.

HEAD FLY (Hydrotea irritans) is associated with the spread of summer mastitis.

MIDGES (Culicoides spp.) are responsible for the spread of the blue tongue virus 


To help combat this, we have introduced a new product to our molecare range - Deltamole for the control of biting and nuisance flies, biting and sucking lice.

Animal based control:

All fly-killing products designed for cattle are from the synthetic pyrethroid group. These kill the fl ies by affecting the nervous system. Pour-ons such as Deltamole, Spot-On, Flypor or Swish are generally applied along the back of the animal and spread from the application site to protect the whole body.

o They offer fly protection, from 4-10 weeks. And many are also protective against other ectoparasites such as mites and lice

o Re-application may be necessary at shorter intervals depending on the level of fly challenge and the diluting effect of rain

o They generally have little or no milk withhold so can be used on dairy cows. Meat withhold periods vary between products - an important factor to consider in animals close to slaughter ‘Flectron’ fly tags are also available. These are ear tags impregnated with a synthetic pyrethroid.

o They are designed to last a whole summer season

o Up to 2 tags may be used per animal

o They can be particularly useful in controlling the spread of New Forest Eye

o They have no withdrawal period as there is no systemic absorption of the product

Other fly control products are usually citronella based repellents which can also help with reducing the stress caused by flies to the animal. They will require regular (often daily) re-application to be effective.


• Deltamole is a pour-on insecticide containing the proven active ingredient deltamethrin

• Deltamethrin has a high level of potency compared to alternatives, making it highly toxic to insects with a good safety margin for mammals.

• The unique micronised formulation of Deltamole enables effective spread over the body

• The deltamethrin within Deltamole is highly lipophilic which means it binds onto the natural oil secretions of the coat to improve coverage and provide long protection

• Up to 8-10 weeks’ protection against biting and nuisance fl ies, sucking and biting lice

• Studies have shown Deltamole to be effective in killing midges for up to 4 weeks after application

• Proven deltamethrin pour-on in a micronised formulation

• Apply from bottle or use the molecare applicator gun

• Rainfast, biodegradable and low environmental impact



Use medicines responsibly. Please visit Noah for more information.

Source Details

 624 Mole Valley Farmers Newsletter

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