Chapter 3. Fly pests that develop in manure and waste

Abstract

This chapter covers the groups of true flies (order Diptera) that are considered filth flies. Filth flies develop in decaying organic matter like waste hay and feed, manure, soiled bedding, and even grass clippings. There are five primary species of filth flies associated with horses: house flies, stable flies, Fannia flies (Section 3.1), horn flies, and face flies (Section 3.2). Two of these species, horn flies and face flies, do not reproduce on equine farms because of their inability to develop in any material other than cattle manure. However, because horses are often located in rural areas where there may also be cattle, these flies can also become a pest problem on equine farms. Unfortunately, many of these filth flies look very similar and can be a challenge to tell apart by appearance alone. Some fly management options are species-specific so identification is critical. There are some distinct behavioural differences that, coupled with slight differences in appearance, can be used to identify species of fly pests. These differences are described in each respective section of this chapter. Filth flies are some of the most common flies associated with animal production and as such, there has been extensive research on this group of insect pests. Most research has been conducted on poultry and cattle production facilities. However, in many cases, this information can be used to develop management practices for fly control around horses as well. Filth flies often cause annoyance, and in the case of stable flies and horn flies, can inflict painful bites. In addition, because of their extensive and repeated visitation among animals and their development and feeding in waste and decomposing matter, filth flies can carry and transmit pathogens that cause diseases in horses including the pathogens and parasites that cause pigeon fever, summer sores, eyes worms, sarcoids, and respiratory viruses.