Yellow flies are any of a number of species of biting fly. Around the size of a house fly, a yellow fly has a distinctive yellow body and patterned wings. The flies feed on blood and are not particular as to where they get it. This includes humans, and yellow flies can deliver a painful bite. Several methods are available to help repel yellow flies.

Chemical Repellents

Many chemical repellents are available for repelling yellow flies. These typically contain diethyl meta-toluamide, or DEET, which produces a scent that masks the wearer, making it difficult for the flies to detect the person. Other chemicals, including citronella and geraniol also may be effective. Permethrin-based repellents also are on the market. Labeled for application on clothing only, these repellents come as aerosol sprays. Chemical repellents may prove less effective during peak times of yellow fly season.

Trapping

Yellow flies are particularly attracted to large darkly colored objects that resemble the prey animals upon which these flies feed. A special trap made of an inflatable beach ball painted dark, coated with insecticide and strung from metal or wooden rods will not only attract yellow flies away from populated areas, but also kill the flies as well. Another type of trap, developed at the University of Florida, consists of a blue plastic bucket covered with a sticky substance. The flies are most attracted to the blue color and will land on the bucket, sticking to its surface permanently.

Insecticides

Several insecticides available at home improvement stores and garden centers are rated for killing or repelling yellow flies. These include carbaryl, permethrin and malathion. Apply the sprays to the lower branches of shade trees and shrubs. The sprays remain on the leaves of these plants providing a residual deterrent. Repeated applications may be necessary during a season, as these insecticides tend to degrade quickly and will become ineffective at stopping the influx of new yellow flies to the area.

Personal Protection

When working outdoors during yellow fly season is unavoidable, you may choose to wear protective clothing to prevent attack from these biting flies. A mosquito veil, long slacks and long-sleeved shirts provide coverage that prevents flies from biting.