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Controlling profit-robbing flies

Aimee Robinson for Progressive Cattle Published on 24 March 2021
Flies on cattle

Flies are much more than a nuisance. Their economic impact can reach deep into a cattleman’s pockets.

“Excessive fly numbers affect cattle production in different ways – none of them profitably,” explains Arnold Nagely, DVM. “While cattle are fighting flies, they are not grazing and gaining the weight that they could be. Starting control measures before fly populations build usually yield[s] better results. As with many challenges, prevention or early intervention is prudent. Timely spraying, back rubs and insecticide eartags are among several methods utilized to stay ahead of major infestations.”

Fly control products have evolved over the years to offer producers with better protection for their cattle operations. Nagely shares two of the greatest advancements he has seen since beginning his food animal veterinary career and cofounding Valley Vet Supply in 1985, alongside fellow veterinarian Ray Shultz.

1. Insecticide application methods, which have evolved over the decades. Mist sprayers on ATVs are a popular insecticide delivery tool. Also commonplace today are Fly Killer Kovers for mineral feeders, cattle rubs and even CO2-powered applicators for insecticide capsules, which offer a quick and convenient method to treat small- to medium-sized herds.

2. New insecticide chemicals have become available, particularly as ingredients in insecticide eartags and in the capsules for CO2-powered applicators.

Fly chart

Warm weather provides the perfect environment for a rapid increase in fly populations. Of the different species of flies affecting cattle operations from herd health to operational profitability, there are a number of control methods available to help control flies and dramatically limit profit loss. Let’s review the different fly species and their economic impact – according to data provided by Bayer Animal Health – along with recommended action to take for effective control methods.

Face flies

Face flies can cause reduced grazing and weight loss. In fact, it takes only 12 flies on a cow’s face to potentially reduce grazing time by as much as an hour a day. Face flies also transmit pinkeye-causing bacteria known as Moraxella bovis, plummeting profit by as much as $12 per hundredweight (cwt).

“Pinkeye is a costly problem in cattle, to say nothing of the nuisance and inconvenience of continually treating new cases, just when the operator needs to be in the field or attending to other responsibilities,” says Nagely. “We know the causative agent for pinkeye is likely a moraxella bacteria and that tall seed heads can scratch the animal’s eyes, making them vulnerable to bacterial invasion. But it’s the face flies that spread the disease from animal to animal, and sometimes herd to herd across the fence.”

Horn flies

U.S. livestock producers lose $1 billion annually because of the horn fly, due to decreased feed intake, weight loss and diminished milk production. Horn flies also are linked to summer mastitis outbreaks. A single horn fly can take a blood meal from a calf up to 30 times a day, and the impact on rate of gain for yearlings is colossal, reducing yearling weights by 18%. Compared to yearling cattle experiencing heavy horn fly infestations, those with horn fly protection had anywhere from 15 to 50 pounds greater weight-gain advantage. Additionally, calf weaning weights were 10 to 15 pounds higher when horn flies were controlled on mother cows.

House flies

The house fly causes aggravation in cattle, pen avoidance and reduced feed intake. Like the horn fly, the common house fly also transmits mastitis-causing bacteria.

Stable flies

Costing producers $2.2 million every year, stable flies can cause blood loss, reduced milk production by up to 40% and decreased weight gain by as much as 0.48 pounds per day.

“A common telltale sign of stable fly invasion is grass cattle huddled in the corner of the pasture, rather than out grazing. Or they may take refuge in the pond to keep those flies off their legs and bellies,” cautions Nagely. In addition to wreaking havoc with pasture cattle, stable flies also can be a real menace to show calves around the barn.

cattle rubs

In addition to the fly control methods mentioned above, try not to underestimate the value of regular cleaning around your facilities and property. With some quick cleaning every day or so, you can minimize the fly egg production cycle by removing common fly breeding areas (flies are most drawn to moist areas, such as manure and excess plant material, like old, unused silage.) Keep these tips in mind:

  • Tidy barns and lots, as well as feedbunks.

o Clean barns and lots often, weekly if possible, spreading manure so it dries.

o Remove unused or wet, spoiled feed.

o Spread out or remove uneaten hay to dry quickly.

o Use fly predators, which are cocoon-conquering bugs that kill immature flies.

  • Prohibit the fly population through pasture management.

o Help manage moist, wet areas of pastures through drainage, where practical.

o Keep overburden of plant residue at a minimum by controlling and cutting back excessive weeds and plant growth.

o Use larvicide feed-throughs in minerals, preferably beginning before turnout.

It is crucial for producers to leverage effective insecticides and fly control methods to help keep cattle healthy. Begin methods of fly control early, and practice insecticide rotation for the best results against emerging fly populations.  end mark

PHOTO 1: Protecting your cattle from flies results in healthier animals and improved profits. Photo by Cassidy Woolsey.

PHOTO 2: Cattle rubs remain a viable option for the application of insecticides controlling flies. Photo courtesy of Valley Vet Supply.

Aimee Robinson
  • Aimee Robinson

  • Content Marketing Manager
  • Valley Vet Supply
  • Email Aimee Robinson