With a little planning, you can get a handle on flies before they take over your property. The sooner you begin, the better, since the pests grow so quickly (a housefly develops from egg to adult in just eight days).
Although it's impossible to completely eliminate flies, you can reduce their numbers. Most experts recommend a combination of biological and cultural control and insecticides.
Get to know your flies
"For control, management, and prevention of flies, it is important to know what fly species is causing the problem," says Ludek Zurek, medical and veterinary entomologist with Kansas State University Research and Extension. Houseflies, face flies, horn flies, and stable flies are the main species that bother horses and cattle. Horse flies, deer flies, and horse bot flies may also be present, causing problems for horses.
Houseflies can spread food-borne and animal pathogens, even though they don't bite. "The key to controlling houseflies is a good sanitation program that includes maintaining good drainage, cleaning around feed bunks, under fences and gates, and around water systems," Zurek says. Baits and sprays can also be used.
Face flies are nearly identical in appearance to houseflies, but congregate around the heads of animals. In cattle, their presence can potentially cause reduced weight gain or milk production. These flies are also believed to spread pink eye, which can lead to blindness in cattle. Horses are also bothered by face flies.
Horn flies feed on the blood of cattle and horses and are about half the size of houseflies. They gather on the shoulders, back, and sides of animals but often move to the underside of the belly on hot days, Zurek says.
Horn flies can be controlled with ear tags in cattle, plus sprays, pour-ons, dust sprays, and back rubbers.
Stable flies wreak havoc
Stable flies bite and feed on the blood of people and animals, most often biting them on the legs. "Cattle react by bunching up (thus increasing heat stress) and standing in water, which helps protect them from bites but reduces feeding and decreases weight gain," Zurek says.
According to Philip Scholl, an entomologist who leads the USDA Agricultural Research Service's Midwest Livestock Insects Research Unit in Nebraska, stable fly attacks cause an estimated $1 billion in annual losses to the U.S. dairy and beef industries and can cut yearling steers' daily gain by nearly half a pound.
Horses also bunch up when stable flies become a problem. Crowding into such close quarters can cause heat stress and injury to the animals.
Flies, round bales linked
Scholl says round hay bales may be to blame for the expansion of stable flies from the barnyard to pastures and rangeland. "In the last 10 years, stable flies have become as important a pest of pastured cattle as they once were for confined beef," he says. "The most logical explanation for this increase is the almost ubiquitous use of round bales as a feed supplement for winter-pastured cattle."
The stable flies may be developing in hay bale litter that has mixed with mud, water, and manure, Scholl says. It's also possible that they migrate from breeding sites at nearby farms. Or, Midwestern grazing lands may be repopulated each spring by wind-borne flies from the south.
Scholl and colleagues are beginning a five-year study monitoring stable flies in Nebraska. "The objective is to better understand the flies' biology, ecology, and breeding habitat so we can devise control strategies to be used in an integrated approach."
Until an effective method for controlling stable flies is developed, livestock producers and horse owners can slow their onslaught by minimizing hay waste and accumulation or by spreading wasted hay into thin layers.
Use a combination of approaches
Most experts agree that there's no single solution for battling flies. Manure and sanitation management, known as source reduction, is the most important first step to controlling the problem. Beneficial nematodes can be used for biological control against developing larvae. Parasites can be brought in to attack flies in their pupal stage. The gnat-size wasps are too small to sting humans or animals. USDA-approved fly parasites are available from companies like Kunafin (800/832-1113 or kunafin.com).
Once flies reach the adult stage, sprays, pour-ons, ear tags, rubs, and feed additives can be used to help keep the pests off of animals. Traps can also be effective at this stage.
There are hundreds of flytraps on the market, and most can be used near animals. Besides those featured here, Olson Products (330/723-3210 or www.olsonproducts.com) offers a range of flytraps.
Feed-through fly control is another option for horse owners. Products like SimpliFly with LarvaStop from Farnam (see contact information below) pass through the horse's digestive system, inhibiting the development of flies in the manure of the animal. For this particular product, the company says fly populations can be reduced from 97% to 100%.
Fly sprays made especially for horses are also available. Some are sweat- and rain-resistant, and many offer UV protection and repel flies, mosquitoes, gnats, ticks and lice.
If flies persist, see-through masks can be used to protect horses' eyes and ears. Specially designed, breathable sheets keep backs fly-free.
Also, check with your veterinarian for product recommendations specific to your horses and your location.
Biocontrol Network products trap adult flies without pesticides
5116 Williamsburg Road
Brentwood, TN 37027
The aluminum ARBICO solar flytrap can be used around animals. Bait is placed inside in a bowl, under an inverted cone. Flies enter and are trapped in the chamber and dehydrated by the sun. Includes one bait packet, which lasts five weeks. Cost: $76.90 for trap, $6.25 per extra bait, with discounts on both for orders of four or more.
The Rid-Max flytrap, made from recycled materials, is about the size of a coffee can. It is made of plastic mesh with a one-way trapping cone. Flies fly through into the trap chamber, cannot escape, and die of dehydration. Place the trap over bait (not included with trap but also available). Cost: $10.95 per trap or $99.95 for 12. Bait is $6.25 each or $6.00 each for four or more.
The Fly Finder is a white roll of tape with randomly placed black dots that attract flies. A nontoxic adhesive holds flies until they die. When the tape becomes 90% covered by flies or dust, roll the used portion onto a second reel, which exposes fresh tape. Can be used near animals, including horses. Cost: $35.50 for 6"×300', $99.90 for 6"×1,500' roll, including hardware.
Silva Fly String is pesticide-free, approved for use in dairy facilities, and kills all types of flies, the company says. It can be installed in rows on the ceiling near animals. Can catch up to 150 flies per foot. Each kit includes hardware and 1,600 feet of string. Cost: $71.50 for complete kit, $43.50 per replacement reel.
Farnam Companies, Inc., offers several fly control products
Farnam's disposable Fly Stik contains muscalure, a scientific formulation of a naturally secreted fly sex pheromone that doubles its attracting power, the company says. The sticky surface traps flies and features pictures of flies. It can be used indoors or out, does not contain insecticides, and is safe around people and animals. Includes stick and attractant. Cost: $5.95 for one 24" stick; $9.95 for four-pack of 12" sticks at 866/724-6773 or agriculture.com/go/5604.
Farnam says its field studies show the EZ Trap catches three times as many flies as other sticky traps. It's insecticide- and odor-free and can be used around people and animals. It can hang, stand, or stack on a garden stake, indoors or outdoors. The adhesive is rainproof, and the trap attracts flies and other flying insects. Cost: $6.98 for two at 800/283-2353 or agriculture.com/go/5605.
Farnam's Trap 'n Toss is a disposable flytrap that can be hung up or set down where flies are most active. It attracts and kills flies without insecticides and is safe for use around people and livestock. Each trap holds more than 10,000 flies. Squeeze included fly sex attractant into trap and add water. Dispose of when full. Cost: $3.98 at 800/367-4444 or agriculture.com/go/5606.
The Milk Jugg Trap turns plastic milk jugs into fly traps. Add water and included insecticide-free attractant to the jug, pop on the top, then set on the ground or hang up. Tops can be reused. Farnam says this trap can catch over 35,000 flies. Includes tops and attractant for two traps. Cost: $8.29 pkg.; $4.19 for 2 extra attractant packets at 800/321-0235 or agriculture.com/go/5607.
FlyRelief and Giant FlyRelief bags from Farnam come with hangers. Insecticide-free, disposable traps have attractant built in. FlyRelief catches thousands of flies; Giant FlyRelief traps twice as many. Cost: $3.98 for FlyRelief; $4.98 for Giant FlyRelief at 800/283-2353 or agriculture. com/go/5608.
Farnam's heavy-duty plastic Captivator Fly Trap has a 2-quart capacity and includes one tube of insecticide-free attractant. Squeeze in fly pheromone attractant and add water. One-way entry system keeps flies in the trap. Reusable with available attractant refills. Cost: $5.00; $4.25 for 2 extra attractant packets at 800/356-0700 or agriculture.com/go/5609.
The Fly Terminator Trap and Magnum Fly Trap have 1-gallon and 21⁄2-gallon capacities, respectively. Each includes a patented, insecticide-free fly sex attractant with feeding stimulants. Break-resistant bottle can be reused. Cost: $22.73 for 1-gal. size; $28.95 for 21⁄2-gal. size. $6.28 for 4-oz. bottle of attractant refill at 866/602-3486 or agriculture.com/go/5610.
Farnam's Fly Terminator Pro is a plastic gallon jug that traps up to 35,000 flies. It's insecticide-free and can be used around livestock. The reusable trap features a patented, plastic top that won't rust when exposed to the elements and ammonia. Includes handle for hanging and a patented fly attractant. Cost: $14.75 for trap and attractant; $17.44 for 16-oz. extra attractant (can be used with any jug trap) at 800/356-0700 or agriculture.com/go/5611.
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