Flies are a nuisance to animals and people alike, but they can be controlled. Good sanitation combined with fly abatement products can help suppress a fly infestation.

Most flies reproduce in the manure. The most effective way to treat them is to get a product in the manure that controls fly development. Insect growth regulators (IGR) or insect development inhibitors are bio-pesticides that are fed to cattle and pass through the digestive tract into the manure. When a fly lays their eggs in the manure, the IGR interferes with the development of the larvae so that a mature fly will not emerge.

Wet organic matter is also a reproduction area for flies. Anytime something stays wet long enough, flies can emerge and multiply. Cleaning up around the farm is critical to achieving excellent fly control. Some of the areas to focus on are:

  • Pick up spilled feed around feed bins and the feeding area
  • Mow grass around buildings on a regular basis – ensuring to not leave clumps of grass
  • In pack areas, spread used pack out onto fields within a few days of cleaning the area
  • Make sure all hay is under a roof or cover
  • Remove old silage from bunkers
  • Watch round bale feeders – an excellent area for fly development – move periodically
  • Keep tall weeds or crops away from dairy areas
  • Check waterers for leaks to prevent moisture build up

ClariFly® versus Altosid®

While both considered IGRs, ClariFly® and Altosid® are best used in different cattle housing types.

Altosid® is specifically licensed for Horn flies because of their costly impact to cattle producers. Typically, Horn flies are specific to pastured cattle along with Face flies. Because Face flies fly long distances for a meal and are less picky about where they lay eggs, they can be dealt with separately when they become an issue. Horn flies, however, need only reach numbers of 200 flies/adult beef cow to begin costing the producer money. This value is known as the economic threshold, as the adult Horn fly population increases over this threshold, the economic benefits of controlling them offset the cost of treatment. Altosid® is highly effective in controlling Horn fly populations when supplemented at the appropriate levels.

ClariFly® is a larvicide that works more appropriately for cattle housed in confinement.

Benefits of ClariFly® include:

  • Controls all 4 fly types
  • Can be used in beef or dairy
  • Will not harm parasitic wasps
  • No milk withdrawal requirements
  • Can be fed to calves and heifers/cows
  • Can be put into a pelleted feed
  • Minimal cost

To illustrate the effectiveness of ClariFly® a study conducted at the Miner Institute in Chazy, NY reported a substantial decrease in fly counts over fly season (see figure). The orange line indicates fly numbers on a conventional program (control) and the blue line shows fly numbers on the ClariFly® Larvicide program (treated). Depending on the level of infestation, dealing with all 4 fly types in a dairy operation can result in lost milk production and the intangible costs of disease and aggravation.

Fly Season is Coming


Famo Feeds • 446 Industrial Dr • Freeport, MN • 800-450-2145