Fightin’ Flies

The emergence of pesky insects is one of the few downsides of the spring/summer seasons. Here are some effective methods for protecting your horse.

By Debbie Moors

You’ve seen it: the fly dance. Your horse stomps, shakes, flicks his ears, then swishes his tail. He’s uncomfortable, doesn’t rest easily, and swings his head back at flies between mouthfuls of hay and grass. And it’s not just a matter of comfort--flies spread diseases like salmonella, vesicular stomatitis, pigeon fever, influenza and a host of other deadly illnesses.

This year, you’re determined to get rid of those pesky, biting insects for good. But where to start? Fly control products fill the shelves at your tack shop. You’ve heard about sprays, traps, feed-throughs, and fly parasites. There are a lot of options, and there’s a lot you can do to take a comprehensive approach to fly control. We’ll give you a step-by-step plan for making your property less hospitable to flies, and more like home for your horse.

LAY THE GROUNDWORK
Before you start with any fly control products, your barn and grounds should be clean and dry. Bill Warner, an entomologist and new product development manager for Farnam Companies Inc., points out that there are several hundred fly species that bother horses. The biggest pest for horse owners is typically the standard issue housefly, along with the biting stable fly. Houseflies have sponge-like mouthparts and feed on secretions, manure and garbage. Stable flies feed on blood and bite horses on the front legs, causing them to stomp in response to the pain. Each species has its favorite hangouts and snacks, but no matter which flying pest you’re after, eliminating breeding and feeding areas is critical.

Remove Manure: “Horse dung is housefly candy,” says Warner. “Some people will pick up manure but dump it just a short distance away. They complain that ‘I pick my stalls twice a day, but I still have tons of flies.’ This is because houseflies can travel hundreds of yards in just a few minutes, so completely removing manure off-site weekly--or treatment on site--is required. Removing manure as a breeding source will control a large percentage of the housefly population.” For onsite manure disposal, rake manure out to dry it, when possible (using a manure spreader when convenient), or compost it.

Control moisture: Flies and other biting insects are drawn to moisture. Repair leaky faucets, keep stalls and bedding dry, eliminate wet spots in the barn and pastures, and make sure your barn has good drainage. If possible, drain wet spots in pastures. Some biting insects, like no-see-ums, breed along shallow, muddy areas, so make sure the sides of your ponds and stock tanks are steep rather than gradual to cut down on breeding areas.

Put a lid on it: Keep grain and feeds covered, and make sure garbage is disposed of and under a fly-proof lid. If possible, cover manure piles, too.

Welcome a breeze: If your horses are pastured, give them access to exposed, breezy areas rather than sheltered or wooded spots. Stalled horses will appreciate ventilation--a fan can help keep flies away and will control moisture, too.

Nix neighbors: If at all possible, pasture your horses away from cattle and cow manure, which are magnets for those bothersome horn flies and face flies.

Enlist nature: Barn swallows and bats snack on flies and stinging insects. Hang a bat house near barns or pastures for a little friendly assistance. Barn swallows can be helpful but messy, so be sure to clean up droppings or you may be adding to the problem.

TAKE AIM
Once you’ve eliminated as many fly magnets as possible, it’s time to call for reinforcements. Take a look at the following options for your fly control arsenal.

Barn Spray Systems
How it works: Installers run tubing throughout the facility, attaching misting nozzles (about one for every 12 x 12 stall, and every 20 feet in aisles). Tubing is run to a reservoir that holds a natural insecticide (pyrethrum, an extract of a type of chrysanthemum). The insecticide is mixed with water and sprayed through nozzles for about 34 to 45 seconds. On average, the system will spray about six times a day, killing flies, mosquitoes, and other insects.

Experts say: John Marsh, President of Pro-Tech Livestock in Texas, explains that with pyrethrum, the “knockdown” of insects is extremely fast, meaning that flies don’t survive long enough to develop or pass on any immunity to the insecticide. Pyrethrum is short-lived in the environment--the natural insecticide biodegrades within 30 minutes of spraying. Marsh cautioned that using synthetic insecticides can cause problems because of their toxicity and failure to break down in the environment. They can also wreak havoc on a system. A few hours after mixing, they’ll separate within the reservoir, which will cause misters to clog.

Cost: Cost of the system varies by company, installer and size of facility. Once the system is installed, average monthly usage is about a gallon per nozzle, which comes to about $5 per stall,monthly.

Time involved: The tank will need to be refilled a couple of times a year.

Best for: Motor and pump sizes are available for different size facilities. You can spray in enclosed barns or barns that are opensided. If you have an open barn, the spray won’t be as effective on very windy days.

Caveats: If your manure pile is close to the barn, or you have manure in runs, you’re still providing breeding grounds for flies outside. Some owners choose to spray around the barn premises or install nozzles along the outside of the barn.

Barriers (masks and sheets)
How they work: Provides a cover for your horse--from nose to toes--that acts as a barrier to flies and biting insects. Fly masks can cover just the horse’s eyes, or may extend up over the ears (to protect against biting gnats) or down past the nose for protection against face flies. Fly sheets cover your horse from wither to rump, and some offer neck and chest protection as well.

Experts say: An added benefit of masks and sheets is that many offer sun protection, much like a pair of sunglasses, protecting your horse’s eyes and skin.

Time involved: For comfort and visibility, many manufacturers recommend taking the mask off of your horse at night and putting it back on in the morning.

Best for: If your horse is in a pasture near cattle or other livestock, a fly mask can help protect him against horn flies and face flies (which are typically drawn to cattle). Riders who board their horses at a facility that doesn’t use a fly control program can customize coverage to their horse’s needs. Masks with ear covers can help in parts of the country that have irritating gnats. Fly boots help keep your horse from stomping in response to stable fly bites (on hard ground, some horses stomp so much that they may be prone to arthritis, ringbone or impact-related injuries).

Caveats: If your horse is turned out with other horses, pasture mates may find it entertaining to play and pull on fly sheets and masks. Also, keep in mind that horn flies typically bite horses along the ventral midline, and most fly sheets don’t cover this area.

Biological Control
How it works: Fly parasites are tiny, low flying wasps that use the fly pupa (cocoon) as a host, killing the developing fly so that it never hatches.

Experts say: “The main benefit is that you stop a pest fly before it has a chance to emerge and reproduce. You fix the problem instead of chasing it,” says Tom Spalding of Spalding Laboratories.

“The preferred hosts are houseflies and stable flies, but they will occasionally use the pupa of horn flies.” Water breeding flies--like horse flies and deer flies--aren’t affected by fly parasites. Other benefits? It involves no chemicals and is easy on the environment. Fly parasites also don’t affect beneficial insects in manure.

Cost: For one to five horses, under $20 per month; six to 10 horses, under $30 a month. Plan to release parasites monthly starting in early spring. During the peak fly months--when temperatures are highest--plan to release parasites every three weeks.

Time involved: About five days after you receive them, the parasites will emerge from their pupae to active wasps. Release them around areas where there is moist manure. The first time you release them, it could take about 30 days to see results because they won’t have any effect on flies that have already hatched--only those that are in the pupal stage. So it’s best to start just before you have flies.

Also, because there is a chance fly parasites may be preyed upon by mice or insects, many researchers will put them inside a hardware cloth screen or other device in the shade to keep mice away and help shield the pupae from weather when they’re first released.

Best for: Most horse properties.

Caveats: If your neighbor doesn’t have good fly control, you’ll have neighboring flies paying social calls. Insecticides will kill fly parasites, so avoid releasing them in barns with spray systems. If you spray pesticides on your horse, make sure you’re not spraying them near manure areas.

Feed Through
How it works: Given with your horse’s grain ration, feed-through passes through your horse’s system into his manure, where it prevents larvae and pupae from developing properly.

Experts say: Previous feed-through products raised concerns due to side effects. Newer feed-throughs use a different chemical than the original products. Some horse owners have expressed concern that horses on feed-throughs will test positive for drugs or masking agents. Dr. John Lengel, former director of the Drugs & Medications Program at the United States Equestrian Federation, has said that both Cyromazine and Diflubenzeron are permitted by United States Dressage Federation and American Quarter Horse Association rules with no restrictions and no need to report. If you’re using a feed-through and you aren’t sure if it’s permitted, check with your association.

Cost: About 30 cents to 50 cents per day, per horse; less if purchased in quantity.

Time involved: Depending on when you start feeding the product, you may see a change in fly population in two to four weeks. Feed from early spring through late fall.

Best for: Horse operations of any size. Use in conjunction with traps and topicals. Caveats: If you board your horse, and the rest of the horses aren’t on feed-through, it’ll be ineffective, since flies will breed in untreated manure. Likewise, if you have untreated manure from winter, have it removed or cover it, stacking manure treated with feed-through on top. Also, you’ll want to feed each horse separately.

Topicals (Fly sprays, roll-ons, wipe-ons)
How they work: As a contact repellent or vapor barrier to keep flies at bay. Topicals containing pyrethrums (natural insecticides) and synthetic insecticides kill or “knock down” pests. Products without insecticides typically include citronella and other essential oils to repel flies and pests.

Experts say: The goal isn’t so much killing the flies as it is repelling them. “Killing them (using topicals) is like trying to punch a hole in the ocean,” Warner says. Topicals are best used with other methods. Using a feed-through or fly predators helps take care of flies at the larval stage; then a topical keeps those stray flies under control.

Cost: Varies, depending on the particular product selected and application. In general, the lower the cost, the shorter the duration.

Time involved: For “value” (lower-priced) products, daily spraying if needed, or applying before and during rides. For premium products, apply every five days to two weeks depending upon label instructions. Always follow label directions.

Best for: Protecting horses when away from home, at a show, on a trail ride, schooling, or in pasture. If you board your horse and can’t use other types of control, you may need to use topicals and physical barriers. In addition, topicals may help repel flies that aren’t affected by other products.

Caveats: Wear off and can be short-lived.

Traps
How they work: By luring flies in and trapping them, using scents or attractants.

Experts say: Some traps use attractants that are like the scents flies have naturally, so when flies are trapped and die, they begin to rot, giving off more of the attractant scent. Don’t put fly traps in your barn--they act as lures, and will draw flies into it. Your best bet is to put traps around your perimeter to draw flies away from your barn--and to catch some of those visiting flies.