The flies are attracted to the light and are immediately killed upon contact. An insecticide is a chemical that kills flies quickly. While insecticides are an important part of many fly control programs, much less has to be done with insecticides if manure and moisture are managed properly. The indiscriminate use of any form of insecticide can result in the development of resistant strains of flies and can cause harm to horses, humans, and the environment. What type and brand of insecticide will work best for you will depend on your weather, fly problem, style of management, and each horse's sensitivity.
Insecticides are available in many forms for various applications.
Certain general livestock sprays are not safe for use on horses. Premises sprays are for use in and around buildings. Some are not safe to use on livestock, manure, or bedding. Foggers are disposable cans of insecticide designed for the interior of buildings. To use a fogger, close all doors, set the can to spray automatically until empty, keep the doors closed for 15 minutes, then ventilate the building.