Yellow flies include about a dozen species of deer flies and horse flies. They have yellow to black bodies about 3/8 to 1/2 inch in length. They have stripes on the abdomen and mottled wings. They bite humans and animals for blood, cutting through the skin with their mouthparts. These bites cause pain, allergic reactions and disease transfer. According to Santa Rosa County Extension Service, you can't eliminate yellow flies, but you may be able to reduce the problem.
Wear long-sleeved shirts and long pants if you plan to enter an infested area. Also spray an insect repellent that contains DEET, citronella or geraniol. Insect repellents don't prevent yellow flies from landing on your skin, but they prevent the flies from biting.
Apply insect repellent on livestock to prevent yellow flies from biting. Santa Rosa County Extension Service recommends using pyrethroid pour-ons or permethrin sprays.
Paint a plastic cup bright blue and glue the painted cup upside-down on top of a cap. Smear a sticky material, such as Tanglefoot, all over the cup. The blue color attracts yellow flies and the sticky material traps them. Wear the cap on your head and walk around your yard. This trap works best when you are moving.