Filth Fly Integrated Pest Management Options for Pastured Cattle

By Kylie Sherrill, Technical Services Entomologist - Central Life Sciences

Filth flies can quickly cut into your cattle herds’ bottom line causing lost productivity, vectoring diseases and being a nuisance to humans and animals alike. Cattle operations can face high fly populations if producers allow for fly populations to build unchecked. Cattlemen have many options when it comes to their herds’ fly control plan. There are no one-size fits all or silver bullets when it comes to fly control.

Pastured cattle are most likely to be impacted by horn flies or face flies. Horn flies are the #1 economic pest of pastured cattle, costing the US cattle industry over $1 billion in lost productivity and control measures every year. Populations of 200 horn flies per cow reaches the economic threshold, or the level that starts impacting economic performance. Populations can quickly build into the thousands during the summer months on untreated cattle. Face flies feed on liquid secretions on the face of cattle and are implicated in pinkeye and other disease outbreaks. Both species use fresh cattle manure as larval development sites.

Cattle in confinement will be more likely to be affected by house and stable flies. House flies may not feed directly on cattle but are competent vectors of many diseases such as Bovine Respiratory Disease (BRD), E. coli, Salmonella and many other pathogens. Stable flies are blood feeders with a painful bite, feeding from the legs and undersides of the animals. The economic threshold for stable flies is 10 on the front legs of cattle. Both house and stable flies utilize moist decaying organic matter as breeding and larval development sites.

The best choice available to cattlemen is to create and follow an Integrated Pest Management Plan or IPM plan. An IPM plan incorporates multiple types of fly control methods, relying on both preventative and reactionary methods. Both require understanding the target fly pest and selecting control methods that best fit the cattle operation’s time, resources, and pest control budget. IPM programs follow the adage “An ounce of prevention is worth a pound of cure,” intending on limiting the fly populations before it has a chance to become a problem.

Within IPM, control types can be divided into four groups: cultural, physical, biological and chemical. The first three types are considered preventative control, focusing on breaking the lifecycle and filth fly population by restricting the number of flies that reach reproductive adulthood.

Cultural control methods focus on sanitation. Sanitation measures like minimizing accumulating moist organic matter, maintaining drainage and eliminating unwanted vegetation will limit the areas where filth flies can develop. Areas that can be used as larval or breeding habitat include old hay feeding sites, piles of soiled bedding, bunk lines, poorly managed compost and even areas around commodity sheds.

Physical control methods include traps and screens. Fly traps can be used as easy, mess free population monitoring. Upkeep of structures including door and window screens, and the addition of fans can limit the number of flies that make it indoors to offices and barns.

Biological control methods incorporate augmenting and sustaining filth fly predators and parasitoids. Naturally occurring predatory beetles, parasitoid wasps and dung beetles can assist by preying on the immature larva and disturbing and drying out manure and other larval habitat.

Our last control type is chemical control. Chemical control methods are typically reactionary, but preventative products are available as well. Larvicides, either product applied to the larval habitat like or bio-rational feed-additives fed to the cattle to treat manure as it is produced, are still considered a preventative measure. Reactionary adulticides such as sprays, pour-ons, scatter baits and insecticidal impregnated ear tags can assist in controlling the adult population, but come at a risk. Improper use of adulticide products can lead to genetic resistance to those chemical classes. Applying adulticides on an as needed basis, following the product label, and rotating between chemical classes is recommended to avoid resistance.

Not every fly control product will work for every operation. IPM programs are meant to be built for each unique operation. For more information on Integrated Pest Management and how it can fit your operation, visit https://www.starbarproducts.com/ipm.