Fight Nature with Nature to Remove Flies and Mosquitos

We call them pests for a good reason-because they are. Just when we’re ready to enjoy the summer days, along comes a host of pests to annoy our horses and us. And they can do a whole lot more than just annoy. Many of these critters can share diseases with our horses and us, from itchy sores to deadly encephalitis. Here we’ll give you the means to manage insects, including habitat control, use of beneficial insects and animals, and mechanical means.

We can discourage many insects by understanding their needs and habitat. All living things need three things: food, water and cover or shelter. We call this habitat.

Food requirements for insects vary from species to species, but include decaying organic material such as manure or plant material, protein such as blood and nectar or a sugar source. They can get water from a stream, wetlands, pond or human-made area like a stock watering tank, birdbath, an old tire holding water or even that annoying leaky faucet behind the barn. They need cover to hide from predators, for traveling, for nesting and for shelter. Cover could come from trees, shrubs, grass, the eaves of buildings or in between the barn walls.

By understanding the needs of the insects we wish to control, we can look at ways to un-invite them to our horse properties.

Habitat Controls
The first line of defense against all insects is to eliminate their habitat by setting up a good manure and mud management system on your horse property.

Keep Pests Away

  • Pick up manure regularly, and cover the manure pile.
  • Get rid of muddy areas and standing water.
  • Use a worm bin for composting food scraps.
  • Use fly parasites, insect-eating birds and bats.
  • Try mechanical controls, such as fly masks, fly sticks and pheromone and bait traps.

All organic material eventually decomposes and leads to mud-which will trap and hold moisture, potentially creating mosquito and biting midge habitats. By removing and composting all manure, bedding and old hay from your pastures, smaller paddocks and pens, and high traffic areas at least every one to three days, you will significantly reduce breeding grounds for flies. Some fly species breed exclusively in very fresh manure (less than 10 minutes old). Twice-a-day manure removal would be most effective against these insects.

Covering manure piles and composting manure will further help kill fly larvae and reduce breeding ground. Covering also speeds up the composting process by regulating the moisture content. The cover prevents the pile from getting too wet in the winter and too dry in the summer.

Confining horses in a small enclosure such as a paddock, corral or pen during the winter and early spring can reduce muddy pastures. These confinement areas are often called sacrifice areas because you are giving up the use of that small portion of land as a grassy area to benefit the rest of your pastures. Using footing materials such as hogfuel (chipped or shredded wood products), gravel or sand in sacrifice areas can also help reduce mud. Three to six inches of footing material will help build up the area, keeping horses out of the dirt and allowing rainwater to drain through.

Identifying the Enemy

Horses (and humans) have to deal with all sorts of insects. These are the major troublemakers.

Filth Flies
Most of the flies that are found near human and animal habitats are nuisances, commonly called “filth flies” because they are highly unsanitary. During the summer, they breed in garbage, manure and decaying organic materials such as old hay and bedding.

Flies carry disease-causing organisms, viruses and bacteria, spreading more than 65 human diseases, including infectious hepatitis, dysentery, typhoid fever and cholera. They also spread diseases such as anthrax, tularemia and vesicular stomatitis to horses and other livestock.

Horses are highly irritated by biting flies, which feed on blood several times a day, usually on a horse’s legs and belly. Fly bites will cause some horses to spend their entire day stomping alternate legs, which can cause concussive damage to legs, joints and feet. Other flies are attracted to the moisture around a horse’s eyes, nose and muzzle. This can transmit diseases and parasites such as conjunctivitis or pinkeye and Thelazia eyeworms.

Flies seek moist, organic matter in which to lay their eggs. An adult female housefly may lay up to several thousand eggs in her short lifetime of approximately 21 days. The eggs can hatch into larvae (maggots) in a single day. In hot weather, it can take only eight days for the eggs to complete the life cycle and become adult flies. The warmer the weather, the faster the flies are produced.

Horse and Deer Flies
Female horse and deer flies typically lay their eggs in damp areas such as wetlands or marshes. Horses pastured near these areas may be prone to attacks by these very painful and aggravating insects. Female horse and deer flies cut through the skin of the animal with knifelike mouthparts to feed on blood. The wound continues to bleed after the fly leaves, often attracting face flies.

Sometimes these insects are so large that even from a distance you’ll see them chasing your horse around the pasture. Just several of these flies can be extremely annoying or even dangerous for horses, causing panic and fatigue.

Biting Midges
Biting midges, often called punkies or no-see-ums, are tiny gnats that inflict painful bites and suck the blood of their hosts, both man and livestock. Biting midges live in the mud and moist soils around streams, ponds and marshes.

These weak-flying insects are out primarily at dawn and dusk. They tend to feed on a horse’s belly as well as the mane and tail areas.

Horses often become allergic to the bites, scratching and rubbing these areas raw and causing worse skin problems. This condition has several names, including sweet itch and summer dermatitis. Biting midges can carry and transmit diseases harmful to horses, including onchocerciasis, a roundworm infestation in the skin of horses.

Installing gutters and downspouts on your barn and directing water away from paddocks and other high-traffic areas will further reduce mud. Divert rainwater to stock watering tanks or to low-traffic areas of your pasture.

Stagnant water-water that has not been moving or added to (such as from rain) for four days-can be a breeding site for mosquitoes in amounts as small as a half teacup. Mosquito habitat patrol includes:

  • Dumping, scrubbing and refilling all stock watering tanks at least once each week.
  • Checking for clogged rain gutters and cleaning them out.
  • Checking for containers and places where water may collect. Once each week empty water from flowerpots, pet bowls, birdbaths, swimming pool covers, tarps on manure piles, buckets, barrels and wheelbarrows.
  • Getting rid of old tires and other items that collect water. Be sure to check for containers or trash in places that may be hard to see, such as under bushes or around your home.
  • In pastures or paddocks, consider an automatic waterer. That way water is always circulating and does not stagnate, so it doesn’t provide habitat for mosquitoes.
  • To prevent fly and wasp food sources, in warm weather keep garbage in tightly wrapped plastic bags and containers with secure lids. If you’re putting organic waste in the garbage can, wrap it in absorbent material such as newspaper to dry it out. If you are saving organic kitchen waste for composting, store it in sawdust to prevent odors from escaping. A worm bin with a snug-fitting lid is the best option for composting kitchen scraps. Do not compost meat, bones, fat or dairy products because they are likely to encourage vermin.
  • When recycling plastic or glass containers, rinse them free of any remaining food or liquid before putting them outside. The yeast in dirty beer bottles, for example, can attract yellow jackets or flies.

Some insects, such as face flies, biting midges and deer or horse flies, do not like to enter darkened barns or stables. Providing your horse with a shelter area and stabling horses before and during dusk may help them escape heavy attacks of these miserable creatures. Biting midges and mosquitoes tend to be poor flyers, so good ventilation or even a fan safely placed outside a stall to create air movement may help. Inside barn areas, consider using fluorescent lights, which are less likely to attract mosquitoes, and fine screens on stable doors and windows.

Whenever possible, graze horses on your higher and drier pastures at the beginning of the summer and save the lower, damper pastures (which harbor mosquitoes, deer flies, horse flies and biting midges) until later in the summer when those pastures dry out. Avoid pasturing horses at dusk and dawn, when insect activity is greatest.

Harrow (or drag) manure piles in your pastures regularly. Harrowing spreads manure so that plants can use the nutrients and organic materials. Spreading also dries out manure, making it less attractive as fly habitat.

For yellow jackets and paper wasps, eliminate their dwelling sites. To keep wasps out of home wall voids, attic spaces and other interior habits, seal any cracks, gaps and holes. For air vents, install small-sized wire screens. Use caulking or weather-stripping along doors, window ledges, rooflines and foundations. If you don’t have a screen door on your home, simply close the door when preparing meat, fish or sweets.

When eating outside, clean up spills and leftovers quickly. Don’t leave beer or soda cans open or lying around because yellow jackets can crawl into the opening-a nasty surprise for someone who goes for a drink from one.

To avoid wasp attacks yourself, when you go to the barn or on a trail ride avoid looking and smelling like a flower or a picnic. Don’t wear perfumes or bright colors, such as red, light blue, yellow, orange or neon colors. White or dark colors are thought to be the least attractant. Wear heavy, long-sleeved clothing when trail riding because yellow jackets can sting through lightweight fabrics.

Beneficial Insects and Animals
Fly parasites are tiny, gnat-sized, nocturnal wasps that lay their eggs in the developing pupae of flies, thereby reducing or nearly eliminating the fly population. You can buy commercially raised fly parasites from a number of sources. Check the ads in magazines and look in your farm supply catalogues. Local garden stores that sell beneficial insects such as ladybugs might carry fly parasites as well.

To be most effective, fly parasites should be released early in the fly season and every four weeks thereafter. They do not harm humans or animals in any way. In fact, you probably won’t even notice their presence nor how well they are working until you visit other farms that don’t use fly parasites. Most horse folks find them to be a highly successful and economical control option.

Encouraging insect-eating birds to move into your yard and barn area is a highly effective and entertaining means for reducing the flying insect population. Swallows can be a tremendous asset to horse places. One swallow consumes about 6,000 soft-bodied flying insects per day. That’s better than any bug zapper and safer than insecticides.

No matter where in North America you live, there’s a species of swallow that will be glad to help you control flying insects on your farm – Tree Swallows, Violet-green Swallows, Purple Martins (they are swallows, too), Cliff Swallows, Cave Swallows and Barn Swallows are several examples. During the spring and summer, swallows can be seen diving and darting through many horse farms and neighborhoods.

Identifying the Enemy

Surprisingly, mosquitoes play a vital role in a healthy ecosystem. Adult mosquitoes are important pollinators. The larvae and pupae are key food sources for fish and other aquatic life. However, mosquitoes spread many serious diseases, including malaria and West Nile virus for humans; Western, Eastern and Venezuelan encephalitis in horses, as well as West Nile virus; and heartworms for dogs.

Mosquitoes require moist surfaces and stagnate water to breed in. Anything that will hold just a small amount of water will do – old tires, toys, flower pots, birdbaths, dog water bowls, stock watering tanks – or muddy horse paddocks. Prime feeding time for mosquitoes is at dusk.

Yellow jackets and paper wasps are also beneficial insects that inadvertently pollinate flowers and prey on many potentially harmful smaller insects such as caterpillars, flies and aphids. “We would have serious pest problems if it weren’t for yellow jackets,” said Todd Murray, entomologist for Washington State University Extension. “In fact, yellow jackets are used as biological control agents in corn, cotton and tobacco crops. A few well-placed nests can clean up acres of crops of many pests.”

Most of us recognize wasps easily. Yellow jackets are colored in the universal signs of danger: yellow and black. Paper wasps, docile cousins of the yellow jackets, are often confused with their more aggressive relatives, but are usually not a problem to live around. Paper wasps are slightly less gaudy looking with a thinner “waist” and a longer, more slender body.

The easiest way to tell the difference between the two is in their nesting habits. Paper wasps create nests one cell deep, forming a single comb that resembles a small, upside down umbrella. Their small combs are often seen under barn eaves, doorways, light fixtures and even under barbeque grills. The yellow jacket nest is large and most commonly underground, often in an old rodent tunnel. Above-ground nests are the familiar large, round, papery ones resembling an oversized football.

In late summer and early fall (especially when there’s been a warm, dry spring) yellow jackets can become particularly problematic. With their strong drive for protein and sugar, they often end up at our picnic tables or garbage cans looking for ham sandwiches, spilled soda pop or spoiled fruit.

Because they come in contact with garbage and filth flies, they can carry diseases such as E. coli and salmonella. Yellow jackets are particularly aggressive insects, and unlike bees, each yellow jacket can sting repeatedly. An injured yellow jacket can emit a scent that calls fellow workers to their rescue – en masse. Like bee stings, people can react very violently to yellow jacket stings and can experience anaphylactic shock as an allergic reaction.

If you collect horse and dog hair and set it out in tufts, you can watch the antics as the swallows swoop and dart to snatch up bits as nesting material. You can buy or build nesting boxes specific to the type of swallows in your area, and the birds will easily accept them. Consult your local Audubon Society, birding organization, cooperative extension office or the library for more information on nesting boxes and how best to display them.

A good way to reduce the nocturnal insect population is to encourage bats to take up residence nearby. Bats play an important part in every healthy environment. Around the globe, bats are the primary predators of many insect pests that cost farmers and foresters billions of dollars annually and spread human disease.

In North America, the little brown bat can catch up to 1,200 insects in an hour. That’s more than 8,000 insects an evening. In Europe, bats are highly valued and protected because of their insect-controlling capabilities. Europeans build and display “bat houses” much the way farmers do with Purple Martin houses in the Midwest.

Bat houses can be placed on a barn, pole, tree or the side of a house. The best habitat for bats is within a half-mile of a stream, lake or wetland. Bat houses need to be placed by early April, and it can take up to two years for a bat colony to find your house. Order bat houses through garden catalogues, purchase them at stores or check your local Audubon Society, cooperative extension office, the library or the Internet.

A word of caution: Because of the concern for rabies, which bats or any wild, warm-blooded animal can carry, consult your veterinarian for his or her recommendations on vaccinating your horses against rabies, even if you don’t have bat houses on your property. And just as we would do with bees or an unfamiliar dog, you should always leave a bat alone. Bats are not aggressive, although they may bite to defend themselves if handled.

Mechanical Controls
Fly masks are available in several styles and provide an excellent mechanical barrier against flies. Horses learn to love them and will come willingly to put them on. Some fly masks protect the eyes, while others also protect the ears and jowls. Fly sheets are cool, open-weave, mesh blankets that keep flies from pestering the horse’s body. Fly boots, which protect the horse’s legs, are also available.

Several types of simple insect traps can be useful for reducing the flying insect population. Perhaps one of the cheapest and easiest is flypaper, tape or sticks. This is the old-fashioned type of coiled sticky tape you uncoil and attach to the ceiling and when insects happen across it, they get stuck. Some varieties also contain an attractant to further entrap insects.

New variations include orange or yellow fly sticks – sticky tubes with an attractant that you hang from the ceiling of the barn or stall. The Fly Stik Jr by Farnam is an especially useful product that contains no insecticides, poisons or hazardous chemicals. The disadvantage to any of these sticky products is that when they accidentally fall into your hair or your horse’s tail it’s a nasty mess. They work effectively, though, so use them, but choose your locations carefully.

Pheromone traps are simple jars with one-way lids. The traps are placed in barn areas where flies hang out. A small amount of pheromone solution, a natural substance to which flies and yellow jackets are attracted, is placed in the jar. The insects buzz into the jar, can’t get out and die. Traps are sold by different companies under various names such as Trap-A-Fly, Venus Fly Trap and Fly Terminator. Check farm and horse supply catalogues.

Bait jars are another effective option for trapping flies and wasps. You can make your own fly bait jars very cheaply and easily.

Take an old mayonnaise or similarly sized jar and punch several holes through the lid. Then put in a few pieces of raw hamburger or fish and about three inches of water in the bottom of the jar. Set the jar in a safe place where it won’t be stepped on, and very soon the flies, attracted by the smell of the meat, will make their way into the jar and eventually drown.

The disadvantage to this method is that it can be smelly and particularly attractive to your household dogs. But it is a very useful, old-fashioned method your grandmother probably used on her farm!

Several commercial brands of pesticide-free bait jars and bags are on the market. A food attractant is used in these that activates when dissolved in water. Lured by the scent, flies enter the trap through the yellow top cap and drown in the water. The convenient bags come ready to use and are easy to dispose of when full. Some are also reusable. RESCUE!® makes several types of disposable and reusable fly and yellow jacket traps.

Good-bye Bugs
The key point to keep in mind when trying to manage insects is to strive to reduce their food, water and cover sources. After you have their habitat under control, go after the adult bugs with birds, bats, fly parasites and mechanical methods. Your farm will be a lot different than ever before – and you, your horses, your neighbors and the environment will be a lot happier and a whole lot healthier.


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