Managing biting gnats around poultry and livestock

What are gnats?

• Gnats are small (1/16 inch) flying insects also known as black flies, biting gnats, or buffalo gnats.
• Gnats are dark in color with broad wings and short legs.
• Female gnats have mouthparts that allow them to cut a hole in the skin and feed on the blood that seeps into it.
• During feeding, the gnat injects anticoagulants and some toxins.
• There are 30 species of gnats in Minnesota.

Gnats can become a nuisance or problem when they create large swarms. The common gnat species in Minnesota are typically abundant from April to October. Unlike mosquitoes, gnats feed during the day and are often active for a few hours after dawn and before dusk. They are most active on calm days and in forested areas.

Gnats can harm livestock

Gnats attack a variety of domestic and wild animals. Often, they develop itching, bumps and redness at the bite sites from foreign proteins and toxins left by the gnats. But, the intensity of these reactions will vary by animal. Gnat bites can take weeks to heal.

• Excessive gnat bites can lead to severe blood loss. As a result, milk, meat and egg production may drop.
• Gnats target the ears, neck, head, teats and belly of cattle.
• Gnat swarms can interrupt the grazing patterns of livestock.
• Poultry can become anemic from a large attack of gnats.
• In extreme cases, gnat saliva can cause a type of toxic shock that can kill vulnerable animals.
• Gnats may kill poultry by swarming and suffocating them.

Signs of gnat bites

• Poultry may have scabs, cuts and swelling on their faces and combs, and blood-stained feathers on the head, neck or wings.
• Livestock will have small scabs and cuts that may drip blood.
• Bites may look like a reddened welt with a wound in the middle.
• Ears may also be swollen.

Preventing gnat attacks

Gnats breed in or near fast-flowing water and can travel up to 11 miles, which makes them hard to control on farms. Help limit bites and attacks on your poultry and livestock:

• Keep livestock and poultry away from potential gnat breeding sites.
• Provide shelter from gnats, especially during the morning and evening hours.
• Set up fans for livestock and poultry. Gnats can’t fly well with a lot of airflow.
• Ensure poultry have access to a coop. Install window screens that have at least 24 mesh per inch.
• Apply insecticides with the active ingredient permethrin to help kill or repel gnats.
  • Always follow all label instructions when using an insecticide.
  • You will likely need to reapply insecticides.