Fly Control in Horses

May 16, 2022

Written by Central Life Science

Equine Operations
For many horse owners, fly control is more about health and animal comfort than profits. Flies also affect horse owners and the surrounding environment in many negative ways.
Horses’ environments can vary greatly. Consequently, they are exposed to many different fly species. ClariFly® Larvicide, a feed-through insect growth regulator, is designed to control pests from a wide variety of species, including house flies, stable flies, face flies, and horn flies. Unlike conventional fly control methods like spray-on insecticides, ClariFly® Larvicide does not provide a direct kill to adult flies but rather controls the larvae before they can become adults. It is important to point out that ClariFly® Larvicide should be one part of an integrated pest management program that includes cultural, physical, biological, and biorational controls.
Understanding the Problem
There’s no getting around it; where there’s warm weather and horses, there are flies. Specifically, there are house flies, stable flies, face flies, and horn flies. House flies and face flies feed on the horse’s eyes, body orifices, and manure. They can spread fecal bacteria and are vectors for costly diseases that affect both humans and horses. Notably, they can spread diseases like E. Coli and Salmonella to humans who spend time around the animals. Stable flies and horn flies give horses painful bites that can turn into welts; infestations of these biting flies can upset even the calmest horses.
Research shows that only about 5% of house fly and stable fly populations will reside on the horses themselves. The rest will perch on nearby fencing, ledges, and vegetation. To identify perching sites, horse owners should look for “fly specks” – that is, small brown spots of fly waste.
Fly Management Through IPM
Horse owners should be encouraged to control fly infestations with complete integrated pest management (IPM) program. In addition to a feed-through, an IPM program incorporates several routine practices and control methods that help keep fly populations in check.
Building an IPM program can be broken down into three phases; planning, implementation, and evaluation.
  1. Planning
    1. Inspect fly populations to establish areas of heaviest infestation
    2. Establish a cost-effective means of control
  2. Implementation
    1. Cultural Control with manure management and weekly replacement of bedding
    2. Physical-Mechanical control with facility maintenance
    3. Biological Control with naturally occurring fly predators
    4. Chemical Control with larvicides, sprays, etc.
  3. Evaluation
    1. Monitor fly populations
    2. Document areas treated and methods used  
    3. Adjust program according to results
How Feed-Through Products Work
Conventional insecticides – often referred to as adulticides – kill flies by attacking their nervous systems. Feed-through products such as ClariFly® Larvicide work by interrupting the fly’s life cycle rather than through direct toxicity. The active ingredient in ClariFly® Larvicide specifically targets flies in the larval stages of pupation by disrupting the proper development of an exoskeleton. Without an exoskeleton, flies are unable to survive into adulthood.
When a feed-through like ClariFly® Larvicide is mixed into feed or feed supplements, horses ingest it as part of their daily intake. It then passes through the animals’ digestive systems and ends up in their manure, where flies lay eggs. It is here that the fly life cycle is ended. Use of ClariFly® Larvicide can result in more than 96% reduction in fly emergence in treated manure*.
For best results, horse owners should add ClariFly® Larvicide to their feed supplements 30 days before fly emergence (typically when average daily temperatures reach 65 degrees) and continue to do so throughout the season until 30 days after the first frost. To learn more about how ClariFly® Larvicide can protect equine, contact your local Co-op.
ClariFly® Larvicide Formulations
Selecting the right formulation of feed through is the key to effectiveness. To find out which product best suits your needs, contact your local Co-op to get more information.
ClariFly® Larvicide Formulation:
  • ClariFly® Larvicide Blocks and Tubs – Ready-to-use formulations with a choice of .01%, .02%, .04% and .08% active ingredient levels.
For more information on fly control options for equine contract your local Co-op. For more content like this, check out the latest issue of The Cooperator.

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