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  • Writer's pictureGavin Kenny

Fly Control for Cattle, Let Help.

Updated: Jun 5

Control flies on your property
Pest control flies

Fly control for cattle,

As dairy and beef systems have intensified, the need for effective fly control programs has grown. These programs must combine cleanliness with chemical, biological, or physical controls—or a mix of all three, depending on the farm's specific needs.

Flies begin breeding at the end of March.

No farm can completely eliminate flies or the need for controls, but it is possible to significantly reduce populations and the amount of chemicals required.

Starting early in the season, Controlling flies before they start breeding is more effective than trying to manage an established population.

Problem Flies in Ireland, the main flies causing economic losses in herds are stable flies, horn flies, house flies, face flies, and head flies. Each type poses different threats, from spreading diseases like summer mastitis and causing irritation that leads to feed inefficiency and weight loss. However, control methods are generally consistent across fly types.

Control Methods

Chemical Pour-ons, Fly control for cattle

Several products, including synthetic pyrethroids like permethrin and deltamethrin, can be applied to animals' backs. Typically, three or four treatments are needed per summer. Ear tags containing cypermethrin offer season-long protection but may require multiple tags in heavy infestations.

Effectiveness: Highly effective; most kill flies on contact.


  • Easy to use

  • No milk withdrawal requirements

  • Can be used during pregnancy and lactation

  • Effective against major fly pests


  • Limited protection for the udder area

  • Potential resistance issues

  • Possible future restrictions on synthetic compounds

Chemical Sprays

Insecticides can be applied via knapsack sprayers or spray arches.

Effectiveness: Highly effective but may wash off in heavy rain.


  • Can target specific areas like udders

  • Suitable during high-risk disease periods


  • Requires good handling facilities

  • Weather-dependent

  • High labor requirement

  • Difficult to apply evenly

Biological Controls

Fly parasites, introduced by trained technicians, inhibit fly breeding by attacking fly eggs and larvae.

Effectiveness: Effective in intensive housed systems but less so in extensive grazing systems.


  • Sustainable

  • Reduces fly populations over time

  • Decreases use of synthetic products


  • Requires bi-weekly distribution

  • Less effective for grazing cattle

Cost: €60.50 per bag, with one bag needed per 100 cows, depending on various factors.

Walk-through Fly Traps

Common in the USA, these traps catch flies as cattle walk through them.

Effectiveness: Reduces local horn fly populations with repeated use.


  • Non-chemical control method


  • Requires regular cattle handling

  • Effectiveness depends on cattle passing through frequently

Cost: Typically homemade, so cost varies.

Stockholm Tar

Applied to udders and flanks, this tar is a proven fly repellent.

Effectiveness: Prevents summer mastitis effectively.


  • Natural product

  • Provides a physical barrier to flies


  • Can be used only on non-lactating animals

  • Messy and time-consuming to apply

Cow Brushes with Insecticide Applicators

Insecticides are applied as cows use the brushes.

Effectiveness: Variable application rates can lead to sub-lethal doses and resistance.


  • Cows enjoy brushes

  • Can be used in buildings or fields


  • Does not treat legs, so ineffective against stable flies

Water Sprays and Misters

Installed above milking parlour doors, these systems mist cows with water.

Effectiveness: Best in enclosed collecting yards.


  • Low water usage

  • Effective short-term barrier


  • Ineffective on flies under cows

  • Operators may get misted too

Fly Hot Spots Sanitation is the first line of defense against flies. Fly eggs and larvae thrive in warm, moist organic matter. Key areas to monitor include:

  • Hard-to-reach spots in housing

  • Calf hutches

  • Accumulated muck under troughs and in building corners

  • Manure storage areas, which should be kept dry and compacted or held in low dry matter lagoons

  • Hay and straw stacks outside

  • Pasture areas with muck build-up under trees or along boundaries, where overstocking or prolonged grazing should be avoided.

Maintaining cleanliness and implementing control measures early can significantly reduce fly populations and associated economic losses.

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