There are a number of different home remedies you can use to repel flies and reduce your horse's risks of experiencing mosquito-borne diseases. For best results, you may want to try or combine several different home-made repellents.
Avon Skin So Soft
Avon Skin So Soft is an ingredient in a number of homemade fly and mosquito repellent recipes. The most common recipe has been said to be used by the U.S. Forest Service and requires mixing a cup of water, a cup of Avon Skin So Soft bath oil, two cups of white vinegar and a tablespoon of eucalyptus oil. Mix all ingredients in a spray bottle and shake thoroughly before using. You may opt to mix in two or three tablespoons of citronella oil, but you must use the plant-based citronella, not the petroleum-based oil used for tiki torches. Some recipes just recommend mixing one cup of Skin So Soft with three cups of water.
Lemon and Rosemary
Purchase a large lemon with as thick a rind as you can find. Slice it into very thin slices. Put the lemon in a bowl along with some rosemary leaves. Boil several cups of water and then pour into bowl. Leave the mixture sitting for 12 hours, then strain and put into a spray bottle. Shake before applying to horse.
Garlic
Garlic has long been used for keeping flies and other pests away from your horse and your barn. Mixing garlic in with your horses feed is a common long-term home remedy for keeping pests, especially flies, off of horses. Hanging cloves of garlic in barns may also reduce the number of flies that come into your barn. You can create a garlic spray by mixing garlic with water and putting it into a spray bottle for external use on horses' skin.
Cleaning Products
A number of homemade fly control recipes call for household cleaning items such as dish soap, detergent and lemon scented wood cleaners. While some of these products may be effective at killing flies, they are not intended to be left on an animal's skin. Consult your veterinarian before using any products (natural or otherwise) on your horse. Some horses suffer from allergies and could experience negative side effects. Homemade fly and mosquito remedies will vary in effectiveness.