Filth-breeding Flies

Even though these flies do not feed on blood, annoyance caused by their movement on and off animals can lead to reduced performance. In addition, they have been implicated in the transmission of numerous pathogens (helminth, protozoan, bacterial, and viral) of people and other animals. Large populations of these adult flies often are found around poorly managed livestock or poultry facilities and become a public annoyance. These are synanthropic flies, ie, they are often associated with human dwellings. The flies are “vomit drop” feeders and fly from feces to food, spreading bacteria on their feet and within their disgorged stomach contents.

All adult filth-breeding flies have similar sponging, nonbiting mouthparts, designed for sucking semiliquid food. The identification of adult flies is probably best left to a specialist. House flies are medium-sized, grayish flies with four dark thoracic stripes. A preliminary identification of blow flies or bottle flies may be made on the basis of the metallic coloring of the adults. Flesh flies are medium-sized, grayish flies with a checkerboard abdominal pattern.

A thorough sanitation program is necessary to control fly populations in and around livestock and poultry facilities. All manure accumulations should be removed at least twice a week or handled properly, if stored on the premises, to minimize fly breeding. If solid manure management practices are applied, efforts should be made to reduce manure moisture. If a liquid manure pit is used, manure should not be allowed to accumulate above the waterline, either floating or sticking to the sides, because this is an ideal site for fly reproduction. Insecticides should be considered as supplementary to sanitation and management measures aimed at preventing fly breeding. Residual sprays providing 2–4 wk control with one treatment may be applied to fly-resting surfaces. Space sprays, mists, or fogs with quick knockdown but no residual action can be used for immediate reduction of high numbers of adult flies. Other measures for control of adult flies include use of insecticide resin strips or various fly baits. These measures also can be applied directly to fly-breeding sources; however, this should be considered only for fly-breeding spots that cannot be eliminated by normal sanitation practices.