As I talk to folks around the state, I get questions and have conversations quite often regarding
parasite control. About 95% of the time it concerns internal parasites and proper methods of
worming. However, horse owners also have external parasites to worry about as well. According
to Dr. Floron Faries, this includes: stable flies, horse flies, deerflies, gnats, mosquitoes, hornflies,
houseflies, blowflies, fleas, and ticks. There are two preventive types of management practices to
control external practices – chemical and non-chemical. The control of population of external
parasites focuses on reducing the off-spring or future generations. That is, breaking the life
cycles of external parasites killing immature and adult stages in the animal’s environment and
the parasites that infest animals.
• Stable flies reproduce in decayed stall bedding, hay, horse manure, lawn clippings, and
aquatic vegetation.
• Horse flies, gnats, and mosquitoes reproduce in or near water.
Horse Fly
• Hornflies reproduce in fresh cattle manure.
Horn Fly
• House flies and blowflies reproduce in decayed garbage and animal carcasses.
• Fleas and ticks reproduce in animals’ bedding and moist, shaded soil.
The best way to prevent external parasites is to practice proper sanitation in your animals’ pens
and barns. For example, properly dispose of decayed wood shavings, vegetation, manure,
garbage, and dead animals. Routinely drag pastures to scatter manure – this will dry out the
matter and discourage larval development. Proper drainage can also go a long way in reducing
the production of gnats, mosquitoes, horseflies, and deerflies. It also helpful to apply a periodic
insecticide application around the premises.
Sprays, fogs, powders, granules, and baits introduce insecticides into the animal’s environment
to kill immature and adult stages of arthropods, especially fleas and ticks. Environmental control
is more effective in controlling fleas and one species of tick than applying insecticides on
Proper stocking rates of animals prevent overcrowding and accumulation of manure and filth.
You should observe animals daily. Healthy animals tend to have fewer external parasites and are
better able to withstand the effects of parasites.
Strategic administration of insecticides (using the right chemical at the right time) on animals
assists in the control of external parasites. When necessary, proper use of chemicals can aid in
breaking the life cycles of external parasites. Animal chemical control of the parasites that live
on animals such as mange mites, ear mites, and lice is necessary because these parasites breed on
the animals and not the environment.
Insecticides are applied to animals either by hand-application or self-treatment methods. Handapplication
methods include: dip, spray, dust, pour-on, spot-on, injection, and oral. While many
of these methods are seen less often in horse care, it is important to be aware of them. Devices
used for self-treatment methods are back rubbers, dust bags and tubes, liquid wicks, neck collars,
and ankle collars. Self-treatment devices, when properly used, are more efficient at controlling
hornflies than hand-application methods.
As a horse owner, it is important to find the method of control that fits the best for your program
or situation. Like many cases, what works for your horse, may not work for others.
References: Dr. Floron Faries – Texas A&M
Haynes, N.B. (2001). Keeping Livestock Healthy
Hoelscher, C.E., Patrick, C.D., & Robinson, J.V. Managing External Parasites of Texas
Livestock and Poultry
Kahn, C.M. (2010). The Merck Veterinary Manual.