Working with Nature to Control Nature


Eco-friendly pest-control options

By Kara L. Stewart

Reprinted from April 2018 USDF Connection magazine

Horses and their accoutrements naturally attract a variety of pests. Although we can’t eliminate every stable fly or barn mouse, we can implement horse keeping strategies and eco-friendly methods that will make our facilities less attractive to the most common pests.

From fly control to rodent reduction, these tips from experts and fellow USDF members will help you put out nature’s “no trespassing” signs for the most common pests.

Job One: Cleanliness

The first step in pest management is facility cleanliness and sanitation. Without it, all our efforts and other methods will be less effective.

Good manure- and mud-management programs reduce breeding grounds for pest insect populations (see “Pests Begone! Best Practices for Horse Farms” on page 46 and “Large-Scale Manure Management” on page 48). Clean, secure feed and tack rooms make your facility less attractive to rodent populations; and mown areas near barns, paddocks, and pastures help keep ticks at bay.

Next: Address Water, Food, and Shelter

Lush pasture looks bucolic but can harbor pests both annoying and dangerous. These horses sport fly masks, an eco-friendly means of warding off nuisance flies.

Every living creature—those we love and those we don’t especially care for—has the same three needs for survival.

“When we design a least-toxic approach to pest management,” explains Horses for Clean Water creator and director Alayne Blickle, “we can leverage the availability of water, food, and shelter to decrease the populations we don’t want and increase the populations we do want.”

Blickle implements her program’s environmentally sensitive horsekeeping approach at her Sweet Pepper Ranch in southwestern Idaho.

“For example, if we don’t want mice and other rodents in the barn, we store grain in metal containers and pick up spilled feed to reduce the food supply,” she says, “and we keep the floors clean of potential nesting materials to reduce shelter. Then, to increase populations we do want—like beneficial birds, bats, and insects that eat pests—we install bird and bat houses and create appealing habitats with native plants to attract beneficial wildlife.”

Integrated Pest Management: Fly Control and More

To attract beneficial wildlife, offer them safe digs. This nesting box is built for a barn owl, one of several birds of prey that dines on rodents, while bats and other bird species keep flying insects in check.

The multi-pronged strategy of IPM controls insect pests with several components, addressing pest reduction from various angles to reach a more complete solution. Its basic building blocks include:

  • Sanitation (manure management)
  • Biological control (natural predators)
  • Physical or mechanical control (fly masks and traps)
  • Chemical control (insect repellents and feed-through products).
  • And while IPM was designed to reduce pest insects, the same components can be used to control the presence of rodents and other animal pests.

Control Tips: Flies and Ticks

Fly-trap bags and other devices remain an easy, “green” way of reducing the insect population

We may lump all flies into one category (under “A” for annoying), but there are several species, and each has its own breeding requirements and life cycle.

“Filth flies—house, stable, face, and horn flies—breed in manure and similar moist locations,” says Erika Machtinger, PhD, CWB, assistant professor of entomology at Penn State University’s College of Agriculture Sciences in University Park, PA, and a Certified Wildlife Biologist. She’s also a USDF silver medalist and has competed through the intermediate level in eventing, so as a rider and horse owner she understands the need for effective fly control.

“But tabanids—deer and horse flies—breed in water, as do mosquitoes, and each species has different feeding behaviors and territories,” Machtinger continues. “That’s why a single pest-control strategy won’t work as well as a broader approach.”

Biological Fly Controls
Parasitoids. When sprinkled on fly-development sites, these tiny, nonstinging, wasp-like creatures eat fly pupae, thereby reducing the number of adult flies. It’s important to start application before fly populations increase and to reapply at regular intervals.

Birds and bats. Bats and many species of birds (including swallows, martins, and swifts) can consume hundreds of flying insects every hour. “To attract these helpful predators, install bird and bat boxes around your property,” says Blickle. Box designs and locations differ for each species, so check with your local Department of Fish and Wildlife, extension office, or bird-watching groups.

Ventilation. Although it’s not a true biological control method, designing facilities to maximize natural ventilation can help thwart nuisance flies.

“I ride in a covered arena with open sides,” says USDF secretary and USDF Connection editorial advisor Margaret Freeman, of Tryon, NC. “The breeze that comes through the arena cuts the number of flies dramatically as compared to the still air in an indoor arena or a closed-in barn. And the air quality is so much better, as well.”

“How troublesome your pest problem can be depends a huge amount on your local conditions,” says Freeman, who is a former editor at the consumer-focused newsletter Horse Journal, which regularly tested fly-control products. “Flies, no-see-ums, mosquitoes, and ticks can be more troublesome in woody or swampy areas.” Her observation further highlights the need to tailor your pest-control program to the micro-climate at your dressage facility.

Physical Fly Controls
Fly masks, sheets, and leg boots. Offered by numerous manufacturers in a range of fabric types, styles, and features, these physical barriers literally come between your horse and annoying insects.

Fly traps, tape, and paper. Low-tech but effective, these products use super-sticky glue and sometimes an attractant to lure insects. Correct placement is important because different species congregate in different areas.

Bait traps. Most traps, whether jugs, jars, bags, or other designs, use an attractant/water solution and have a one-way entry. Depending on the design, flies either drown or dehydrate. Single-use bags can be disposed of in the trash when full, and more eco-friendly styles allow more bait to be added during the fly season. Try several kinds to find what works best in your area.

USDF member Jennifer Cross keeps two horses on a small farm in West Suffield, CT. Because the land borders acres of wetlands, her fly problem was huge.

“About ten years ago, we purchased an Epps Biting Fly Trap,” Cross says. “I didn’t really think it would work, but it’s been incredibly effective, and every year we have fewer flies.” Follow the manufacturer’s instructions closely about where to locate it, she advises.

Chemical Fly Controls
IGR. Insect growth regulators, such feed-through fly-control supplements Solitude or SimpliFly, reduce fly populations by preventing fly larvae from developing exoskeletons, which disrupts the life cycle. These products work best when all horses at a facility receive the supplement.

Nontoxic fly-repellent sprays. Commercial brands contain plant extracts and other “green” ingredients. (Keep in mind, however, that a claim of “natural” does not necessarily mean that a product is safe—or effective.) Local insect populations and other factors can affect results, so try several to find what works best in your area.

Essential-oil sprays. Alesha Desharnais, a USDF member from Billerica, MA, blends top-quality citronella, rosemary, cedarwood, peppermint, and eucalyptus essential oils with distilled water and witch hazel. “I spray myself and the horses before I ride or take them out for a lesson. It works well, and it doesn’t cause reactions in chemically sensitive horses.”

(One caution: Because essential oils can be toxic to beneficial pollinating insects, Penn State’s Machtinger advises applying only where intended, staying out of the wind while spraying, and keeping spray away from susceptible habitats.)

Ticks—those hated carriers of Lyme disease and other diseases affecting humans, horses, and other species—are a class of pest that most of us would gladly eradicate if we could. Unfortunately, in the US they are everywhere.

“American dog ticks, Lone Star ticks, or blacklegged ticks—also known as deer ticks—are species known to use horses as hosts and are found in different parts of the country,” says Machtinger.

At equine facilities, “pasture management in critical to reduce tick presence,” Machtinger says. “Keep grass short, remove brush where possible to eliminate habitat, and keep a mowed barrier at least three yards wide between woods and fence lines to discourage tick movement toward pastures.”

Biological Tick Controls
The entomopathogenic fungus Metarhizium brunneum var. anisopliae is a naturally occurring organism that kills ticks but does not harm beneficial insects.

“Commercial products using this fungus have shown to be effective in the Northeast,” Machtinger says. “Use caution when spraying, and follow label instructions for application rates and grazing restrictions. And be aware that some products must be applied by certified pesticide applicators.”

Physical Tick Controls
Check your horse at least once a day for ticks. If you find one attached, use tweezers as close to the skin as possible and pull straight back so the head remains attached.

“Place the tick in a plastic bag labeled with the date and location, and then put it in the freezer,” says Machtinger. If your horse develops symptoms consistent with Lyme or other tick-borne diseases, having the tick will aid your veterinarian in devising the most effective course of treatment.

Chemical Tick Controls
Wipe-on and spray-on products. Those containing the insecticides permethrin or its synthetic cousin, cypermethrin, can provide protection against ticks for many hours. “Apply repellents liberally and frequently, especially after exercise, bathing, or rolling,” Machtinger says. Most compounds break down in UV light, so reapply later in the day. “And make sure to apply repellents according to label rates—a few spritzes generally aren’t enough.”

The down side of these products: They’re not very eco-friendly. Permethrin and cypermethrin are toxic to fish, bees, aquatic insects, and some other species, including cats; and skin exposure or ingestion can cause reactions or other side effects. In addition, their broad-spectrum nature means that they kill beneficial insects in addition to the unwanted pests.

“I strongly discourage folks from using broad-spectrum pyrethroids,” says Machtinger, “and this includes facility-wide fly-spray systems. There is evidence that flies are developing site-specific resistance to the chemicals used in these systems, and that they expose horses and humans to unnecessary contact and respiratory risks.”

Essential oils. “My horses have been diagnosed with Lyme disease and anaplasmosis [another tick-borne disease], so I had to find something that works in the battle against ticks,” says Jamie Reilley, VMD, a USDF member from southern New Jersey. “During tick season, every day I spray my horses with a mix of twenty drops each of eucalyptus oil and lemongrass oil and four ounces of water,” paying special attention to places where she’s found ticks lurking before. “Now, instead of finding one to three ticks a day, I find a total of three during the summer and fall.”

As we mentioned previously, Machtinger suggests using caution and applying carefully to the horse’s body, since overspray of essential oils can be toxic to pollinating insects and can harm vegetation.

Control Tips: Rodents

From the smallest field mouse to rabbits, gophers, squirrels, rats, raccoons, and opossums, rodents can wreak havoc at the barn. In addition to eating (and contaminating) large quantities of feed, they can destroy equipment and property, and expose people and animals to disease.

Start with sanitation controls. It’s worth saying again that keeping the barn clean and orderly goes a long way in discouraging rodents from taking up residence. Well-fitting doors and windows can also help keep rodents out.

To make your place less attractive to raccoons and opossums, Blickle suggests putting away dog and cat food at night and not adding bones, fat, or other food scraps to the compost pile. Keep garbage cans in a secure area until the morning of trash pickup. If you have chickens, put them in a safe coop at night with a secure door and roof, she advises.

A watchful barn cat is alert for rodent prey. Many farms consider a cat a key component of their pest-control strategy. Some cat-rescue groups work to place less-social or otherwise hard-to-adopt felines as barn cats for free or low cost.

Biological Rodent Controls
Owls, hawks, falcons, and other birds of prey. These beneficial birds can help control a variety of rodents. Attract them by installing nesting boxes made for each species. Check with your local extension office or Department of Fish and Wildlife for designs and location tips.

Barn cats. Never underestimate the contribution of a talented mouser in keeping rodent populations in check, especially mice. Each trainer at the Parker-based Colorado Horse Park is assigned a feed stall, says Marion Maybank, the venue’s competition manager and COO. “The trainers are required to keep all feed, treats, and supplements in metal containers with lids. This way, our barn cats can roam through and monitor the feed stalls for mice, and they do a great job.”

Keep your barn cats healthy and protected by neutering or spaying, vaccinating, and providing food and water in a place that’s safe from mice.

Physical Rodent Controls
Snap traps. Old-school and still effective, these traditional mousetraps work best when placed along walls and rodent pathways. Bait the trap for a few days without setting it so rodents lose their fear of the device.

Electronic battery-powered traps. Offered in different sizes for different species, these humanely electrocute the rodent when it walks inside. Bait the trap for a few days without turning it on, and allow the rodents to enter the trap and eat the food.

Ultrasonic devices. These emit sound frequencies that manufacturers claim repel rodents but are unnoticed by humans, horses, cats, and dogs.

Chemical Rodent Controls
Common ingredients in repellent products include peppermint oil, ammonia, capsaicin (the ingredient that makes hot peppers hot), and predator urine. Ask your extension office or local pest-control company for recommendations, and remember that “natural” doesn’t always mean safe or effective.

A Balanced Approach to Pest Control

To limit the spread of disease and to keep horses and humans comfortable, it’s important to keep pests in check. The trick is to get rid of the bad guys without harming the beneficial insects and wildlife that naturally reduce pests and help to keep our ecosystem in balance. By incorporating some of the eco-friendly strategies in this article, unwanted visitors will find your barn (and your horse) less attractive, while nature’s own pest-control patrol will want to move in. It all adds up to fewer pests and a more healthful environment.

Large-Scale Manure Management

Large farms and show grounds need aggressive manure-management systems to keep down fly populations

Because many pest flies breed in manure, large show grounds and boarding facilities design manure-management programs, and they’re always looking to improve their effectiveness.

“The big hunter/jumper shows can bring in nine hundred horses,” says Colorado Horse Park competition manager and COO Marion Maybank. With 28 weeks of competitions a year plus 60 to 100 permanent boarders on the grounds, the Horse Park has to be aggressive about keeping manure under control.

“To contend with this volume of manure, twice a day year-round, all manure is picked up and goes to a pile that’s about four hundred yards from the barns,” Maybank says. The pile is removed weekly during the year; during horse-show season, it’s removed two or three times a week.

Frequent manure removal helps to reduce the overall number of flies on the property, but Maybank is always looking for long-range approaches. “We’re exploring a complete solution of doing our own composting. In theory, we should be able to heat the buildings from warmth generated by the composting manure, and there’s a market for selling the nutrient-rich black soil that results from composting,” she says.

Kara L. Stewart is an award-winning author who has experienced the differences in reducing unwanted pests in the opposing climates of Colorado’s Front Range foothills and now along California’s Central Coast. Her retired Arabian gelding, Eddie, loves his fly mask but isn’t crazy about the sticky fly traps hung in his stall.


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