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U OF M EXTENSION SERVICE

Fly control is a constant challenge for dairy producers, especially in warm weather when moisture, manure, spilled feed, and bedding create ideal breeding conditions. While flies may seem like a seasonal nuisance, they can have significant economic and animal health impacts on dairy operations.

Heavy fly pressure forces cattle to spend energy fending off pests instead of resting, eating, or producing milk. Research shows that stable flies— blood-feeding pests— can significantly reduce milk production during heavy infestations. Flies can also increase veterinary costs and spread diseases among animals and humans, making effective fly management essential for maintaining a productive dairy.

Managing flies is important because irritation causes cattle to stomp, bunch together, and flick their tails, reducing time spent feeding and

resting. These stress behaviors can lower feed intake and ultimately decrease milk production.

Second, flies can spread disease. Many fly species move between manure, feed, animals, and equipment, potentially transmitting bacteria and viruses within the herd. Some flies also spread specific diseases, such as the bacteria responsible for pinkeye.

Different species of flies also affect various parts of the dairy operation and cause different responses in cattle. In Minnesota and across much of the Upper Midwest, the most common problem species include stable flies, house flies, face flies, and horn flies. House flies: breed in moist organic materials such as manure piles, spoiled feed, and bedding. Although they do not bite cattle, they can carry pathogens and contaminate feed and equipment.

Stable flies: appear similar to house flies but are biting flies that feed on blood, often biting

cattle on their legs. Animals may stomp repeatedly or bunch together in response, reducing feeding and resting time. Face flies: typically gather around the eyes and nose of cattle to feed on secretions.

They are a major vector for the bacteria that cause pinkeye.

Horn flies: spend most of their life on the animal and feed on blood multiple times per / day. Infestations can significantly affect grazing and milk production.

Identifying which fly species are present on your farm allows you to target the biggest management bang for your management buck. Next week, we will address a plan of attack for getting ahead of flies on the dairy.

If you have any questions or want to know more about University of Minnesota Extension reach out to Dana Adams at adam1744 @ umn. edu or call( 320) 204-2968.

Fred’ s Home Furnace 1801 Haven Road | Little Falls, MN 56345 320-632-9692 or 320-387-3540 www. homefurnacemn. com