What’s the Buzz on Cattle Flies?

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At some point, anyone with cattle has stood in the pasture and swatted at flies. All of us have seen cattle twitching their ears, or flipping their switch to keep the flies away. Not only are flies an animal health and welfare issue, but they can also impact your economic bottom line. It has been reported that calves grown without any method of fly control can have weaning weights of up to 15 pounds less than calves that have been protected from flies, costing the industry an estimated 1 billon dollars annually in lost production. This is especially a problem during summer calving, making fly control an essential management tool for any summer calving herd.

There are three major types of flies to control on pastured cattle: horn flies, face flies, and stable flies.

Horn Flies

Horn flies are typically very small, less than 1/4″, and are seen on the poll, back, sides, and sometimes stomach of animals. Horn flies feed on animal blood by using their needle-like mouth parts to consume up to 30 blood meals from animals daily. Their eggs are deposited in manure pats and hatch there. Horn flies will travel several miles searching for animals if necessary. Their life cycle can take 10-20 days.

horn flies on cattle

Horn flies feeding on an animal (unl.edu)

horn fly

Close up of a Horn Fly (ufl.edu)

Face Flies

The name “face flies”  is rather self-explanatory. These flies a do not bite, but feed on secretions, such as fluid from the eyes, mucus, manure liquids, or blood from already open wounds. Female face flies are most prominently seen on the faces of cattle. These flies are not only annoying to the animals, but the irritation they cause to sensitive areas, particularly the eyes, can lead to increased susceptibly to the infections causing pinkeye (bovine keratoconjunctivitis).

face flies

Face flies on an animal

Stable Flies

Stable flies are biting flies that feed on the legs of cattle in nearly in management situation. Cattle often react to stable fly bites by stomping their feet, or moving into water to avoid the bites completely. Stable flies seek spoiled organic matter, such as feedstuff from the previous winter, to deposit eggs. Stable flies are considered to begin having an economic impact when populations reach 5 flies per leg. Similar to horn flies, stable flies can lead to up to 0.44 pounds decrease of average daily gain

stable flies

Stable flies on an animal’s legs (ufl.edu)

Check in next week for more on how to control these flies.