This oil blend is designed to repel insects such as fleas, flies, and mosquitoes. Like with any essential oil based repellent, it will not kill these insects. This will not eliminate a flea infestation if you have one, but it will help to prevent one by preventing fleas from jumping onto your dog or cat. It also helps keep flies away from your horse. This little bottle is a concentrate and will make a large amount of diluted spray. It takes 10-15 drops of concentrate to make a liter of spray.