Whether your business is raising dairy calves or milking, no one wants to lose productivity to pests. Insects such as flies, ticks and lice pose a threat to dairy producers, as they can transmit disease, lower weight gain and milk production, and even put health inspections at risk.

Hawkins larry
Senior Technical Services Veterinarian / Bayer HealthCare LLC


Horn Fly

With so much at stake, dairy producers should consider a pest control management system to maximize the potential of their dairy.

To control pests that become a problem in and around your facilities, it is important to understand how the various insects can impact your operation and how to create a strategy to defend against them.

horse fly

Horse Fly


Protecting your operation

Defending your operation and your dairy cattle from potentially damaging pests can be done effectively by dividing your operation into four key treatment areas. These include:

  • On-animal – This treatment focuses on pests that want to take blood meals from your livestock, such as horn flies and ticks. These pests can be controlled by using on-animal treatment, which may include ear tags, pour-ons, on-animal sprays and dusts.
  • Facility – Facility- and pen-premise treatments allow you to target flies in the areas where your cattle feed and rest. This creates a prime location for pests to pass from one animal to another. Treating your facilities with premise sprays, dusts and baits can help reduce the number of pests bothering your livestock.
  • Environment – Focusing on environment treatments includes flies in the areas around your facilities where pests breed. Treating potential pest breeding areas that surround your livestock buildings and feed storage areas with premise sprays and baits plays a significant role in reducing the pest population. Also, spilled feed should be cleaned up to prevent it from becoming a fly breeding area.
  • Feed-through – Several species of flies lay their eggs directly in manure. Feed-through insecticides kill fly larvae as the eggs hatch – before the larvae can mature and continue the cycle.

stable fly

Stable Fly

Identifying your flies

Assuming all flies are alike can hamper your pest control efforts, especially when it comes to attacking the source. To provide effective control, you need to know what type of insect you are dealing with, their feeding habits, breeding areas and preferred resting areas.

  • Horn fly – Horn flies are responsible for the spread of mastitis caused by Staphylococcus aureus. These pests attack the teat and suck blood from below the skin, opening wounds for bacteria to enter the teat canal and cause intramammary infection. Horn flies can also spread other disease-causing bacteria.
  • Face fly – The face fly spreads bacteria (Moraxella bovis) that can cause pinkeye. Pinkeye causes very painful eye lesions that cause the animal to avoid sunlight. For heifers on pasture, that means they are grazing less, thus not gaining and growing at an optimal rate.
  • Stable fly – Stable flies biting cows can lead to cattle bunching, which can cause heat stress in animals. Studies also have shown that stable fly infestations of individual herds estimated median annual per-animal production losses to be more than 300 pounds of milk for dairy cows.
  • House fly – The house fly can be a nuisance to you, your family, your workers and your neighbors. Not only is the house fly a pest in this sense, it also is known to transmit at least 65 disease-causing organisms.

house fly

House Fly

Problems with ticks

While flies can present some serious issues on a dairy operation, ticks can be bothersome bugs as well.Ticks can lead to loss of condition, reduced weight gain and severe anemia from loss of blood.


Gulf Coast Tick

Tick bites can irritate cattle and can cause itching. Affected cattle are prone to infection if they cause open wounds from scratching. Ticks can also pass disease-causing organisms that may lead to sickness and loss of appetite or worse. The American dog tick can cause paralysis.

Rotation for maintaining effectiveness

When developing your insect control strategy, it is important to rotate insecticides over time to minimize development of resistance.

When rotating products, you should consider one that uses a different mode of action (MOA) than the one you are currently using. Modes of action available include:

  • Pyrethroids – Sodium channel modulators that disrupt the normal flow of sodium ions
  • Organophosphates – Cholinesterase inhibitors that prevent the breakdown of acetylcholine
  • Neonicotinoids – Acetylcholine receptor agonists that mimic the action of acetylcholine

Limiting pests’ exposure to any one insecticide MOA helps sidestep the potential impact of cross-resistance and helps reduce selection pressure for resistance by any mechanism, minimizing the emergence of new resistant pest populations.

Use what fits your management style, but be sure to keep your method of fly control active.

For more information on MOA, check out this training module.

Keeping safety in mind

Finally, be sure to read the label and know what personal protection equipment is required for the products being used. Also, be sure the employees applying these products are trained in the proper use of each product and the use of the appropriate equipment. PD

References omitted due to spacebut are available upon request. Click here to email an editor.

Larry Hawkins is a senior technical services veterinarian with Bayer HealthCare LLC. He can be contacted by email.

IMAGES: Images provided by Bayer.