Managing pasture flies like horn and face flies through biological control is a sustainable and effective approach. In a healthy pasture ecosystem, natural predators and processes help keep fly populations in check, reducing the need for chemical interventions.

Dung Beetles (Scarabaeidae)

Dung beetles play a vital role in pasture ecosystems, particularly in managing manure and improving soil health. These beetles, part of the Scarab family, are known for their ability to bury manure, which not only recycles nutrients but also reduces the breeding grounds for pests like horn and face flies. By breaking down manure, dung beetles contribute to soil organic matter, improve soil structure, enhance water infiltration, and provide essential nutrients for grass growth.

There are approximately 90 species of dung beetles in North America, with a variety found in New York’s cattle pastures. These beetles are categorized into three main types based on their behavior:

Dwellers: These beetles live and reproduce within the manure pat, laying their eggs directly in or just beneath the soil surface. Dwellers are the most common dung beetles in the Northeast.

Photo By Hannah Tolz-NYS IPM

Tunnelers: Tunnelers create brood balls from manure and bury them in tunnels beneath the manure pat, laying their eggs within these buried balls.

Photo By Hannah Tolz-NYS IPM

Rollers: Rollers, though less common in New York, form brood balls and transport them away from the manure pat to bury them elsewhere, laying their eggs within these relocated brood balls.

Dung beetles are highly efficient at reducing fly populations by breaking down manure before flies can complete their life cycle.

To identify dung beetles in your pasture, flip over a manure pat with a small shovel or trowel and observe the beetles running around. Besides dung beetles, other beetle families such as rove, water, and hister beetles also inhabit dung pats and prey on fly larvae, further aiding in pest control.

Other Predators of Flies in Manure Pats

Several other beetle families contribute to fly control in pastures:

Rove Beetles (Staphylinidae): These versatile predators are found in various habitats, including manure pats, where they feed on fly larvae and other small insects.

Photo By Hannah Tolz-NYS IPM

Water Beetles (Hydrophilidae): Some species are specialized for life in manure pats, with larvae that prey on fly maggots.

Photo By Hannah Tolz-NYS IPM

Hister Beetles (Histeridae): These beetles thrive in manure and are efficient predators of fly maggots.

Photo By Hannah Tolz-NYS IPM

These beetles, alongside dung beetles, compete for manure resources and directly prey on fly maggots, significantly reducing fly populations.

For more information on Dung Beetles please view the following site: https://cals.cornell.edu/new-york-state-integrated-pest-management/eco-resilience/beneficial-insects/visual-guide-dung-beetles

Poultry and Wild Birds

Chickens can be an effective tool for fly control in rotational grazing systems. By introducing chickens into paddocks about four days after cattle have been rotated out, you give dung beetles time to work through the manure. Chickens then scratch through the pats, feeding on maggots and pupae, reducing fly populations while spreading the manure, which helps dry it out and eliminates breeding grounds. However, managing poultry requires additional effort.

Wild birds, like barn swallows and purple martins, also play a crucial role in fly control. These birds consume large numbers of flies during the breeding season, making them valuable allies. Encouraging a bird-friendly environment by installing and maintaining nesting boxes can help manage fly populations effectively.

Parasitoids

Parasitoid wasps are used to control stable and house flies around barns by infecting their pupae. However, face fly pupae are harder, making it difficult for parasitoids to penetrate them. Although a few parasitoids do infect horn fly pupae, research shows that augmentative releases are not very effective in pastures. Therefore, releasing parasitoids on pastures is not currently recommended. It’s better to reduce insecticide use until a herd reaches the action threshold to protect natural enemies.

Research is ongoing to improve biological control methods for horn and face flies in pastures, including the use of fungi and breeding cattle with greater fly resistance. By leveraging these natural behaviors and predators, farmers can maintain healthier pasture ecosystems and reduce their reliance on chemical controls.