After the long winter endured by producers in most parts of the country, you may actually be excited to see the first flies emerge this spring. But it won't be long until they become a major hindrance to animal and worker comfort, so it is important to formulate a plan now that will minimize their impact later. Cornell Cooperative Extension educator Patricia Westenbroek suggests an integrated pest management (IPM) approach to effectively managing fly populations.

The two primary fly species that plague dairy operations are the housefly (Musca domestica) and the stable fly (Stomoxys calcitrans). House fly populations turn over every 10 to 14 days in warm weather. Because every female lays 150 to 200 eggs, and one pound of manure can contain more than 1,500 maggots, it is important to break their life cycle.

Stable flies are similar in appearance to houseflies with one important distinction - they bite! Large populations of these bloodthirsty pests can reduce milk production in lactating herds by 15 to 30 percent.

The four components of an IPM strategy for fly control are:

  1. Cultural control - Employ effective sanitation practices to keep the environment as clean and dry as possible. Female adult flies love to lay their eggs in manure, decaying silage, spilled feed, soiled bedding and other organic matter. Calf areas also are prime real estate for fly breeding. Clean out and relocate calf hutches regularly, and keep them well ventilated to promote dryness. Scrape manure throughout the farm routinely, and keep areas around feed storage, bunks and water troughs as clean and dry as possible. Your weed whacker and mower also should be fully employed all summer. Excess vegetation around barns, feeders, hutches and manure piles is an ideal fly resting and breeding ground.
  2. Biological control - Insect predators and parasites can help reduce fly larvae and pupae populations. Some - like the hister beetle - appear naturally, while others - like parasitic wasps - can be purchased and released into the environment. It is advisable to begin to release parasites in the early spring to get ahead of the fly population. They perform best in enclosed environments like calf hutches.
  3. Chemical control - There are a wide variety of chemicals available to control flies. Before using a chemical product, check to make sure it is legal for use in your state, and always follow the label's instructions.
  4. Physical control - Tapes, traps and lights are forms of physical control aimed at attracting and killing the adult fly. Employ traps in areas where chemical use is difficult, ineffective or unacceptable, such as milking parlors, milk holding rooms, and feed holding and mixing areas.

Westenbroek notes that none of these control measures will have maximum efficacy on its own, but that they offer tremendous synergies when combined as pieces of a complete plan.

Source: Dairy Calf and Heifer Association