Horse Property Pest Control

Disease-harboring mosquitoes and flies top most horse owners’ list of bugs to beware of, but don’t forget these other horse and barn-harming pests.

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Property Pest Control
Native paper wasps like to build their nests along barn, shed, and arena eaves and ledges. | Photo:

Disease-harboring mosquitoes and flies top most horse owner’s list of bugs to beware of, but don’t forget these other horse and barn-harming pests.

When you think about what bugs are a nuisance on the farm, flies and mosquitoes usually top the list. But other potential pests require your attention—insects that can harm you, your horses, and even your structures. Maybe you haven’t noticed them. Perhaps you’ve ignored them because they don’t seem to be an issue. Or you might not even be aware of them because they are new to your area. It’s time you got acquainted.

Lee Townsend, PhD, extension entomologist with the University of Kentucky, says weather and climate change have profound effects on arthropods. “Mild winters can allow survival of species most commonly associated with more southern areas of the country so the range of some pests can be extended,” he explains. “Early springs and longer growing seasons can mean an extra generation of some insects. This can extend the pest season by one to two weeks.”

Pests expand their range accordingly, possibly appearing earlier and staying longer.

“If horse/stable owners took the time to learn about the biology and life history of pests,” suggests Holly Ferguson, PhD, extension integrated pest management specialist at Washington State University, “they could immediately take measures to mitigate a current pest problem or prevent it from becoming a problem and, at the same time, rely less on short-lasting chemical treatments.”

Here we’ve rounded up some less commonly considered “bug” suspects—from those that destroy structures to those that pester horses—and offer options for their control or elimination.

Carpenter bees

These inch-long black and yellow insects look like bumble bees, but their rear ends are black, shiny, and do not have the bumblebees’ characteristic yellow hairs.

Problem Carpenter bees are attracted to sheltered areas with bare, unpainted, or weathered softwoods. Common nesting sites include eaves, window trim, and fascia boards (which cap the end of rafters outside a building). Each bee creates its own tunnel into one of these areas, and large numbers can build up in an area over time. Their loud buzzing and often aggressive darting can intimidate people and animals. Only female bees are capable of stinging, however, and rarely do.

Options Because carpenter bees overwinter as adults in wood nest tunnels, concentrate on reducing the resident population as soon as activity begins in the spring.

“Liquid sprays of insecticides labeled for carpenter bee control that contain insecticides such as carbaryl, cyfluthrin, or permethrin can be applied as a preventive to wood surfaces that are attracting bees,” says Townsend. These insecticides’ residual effectiveness usually only lasts one to two weeks, however, and you might need to repeat the treatment. 

Treat existing tunnels by puffing an insecticidal dust (e.g., 5% carbaryl) into the nest opening. Leave the hole open for a few days to allow the bees to contact and distribute the insecticide throughout the nest galleries, Townsend says. Next, plug the entrance hole with a piece of wooden dowel coated with carpenter’s glue or wood putty. This will keep bees from using old nesting tunnels again. Aerosol sprays labeled for wasp or bee control might also be somewhat effective.

Townsend suggests keeping horses, humans, and other animals away from treated areas until the spray has dried.

Paper Wasps

Several species of native paper wasps live in North America, as does the relative newcomer European paper wasp that was first discovered in the late 1970s on the East Coast and is now spreading west across the nation. Native wasps are usually brown, while European wasps resemble yellowjackets. Only fertilized female paper wasps overwinter. When they emerge in the spring, they select a nest site where they lay eggs and grow a colony. They chew wood and bark to create pulp with which to construct their distinctive -umbrella-shaped multicelled nests.

Problem The eaves and ledges found on barns, run-in sheds, and arenas make perfect locations for paper wasps to build their nests. The annual colonies can grow quite large, and wasps can become very defensive, stinging any human or animal that comes near. Female wasps can sting repeatedly, causing reactions ranging from intense burning, swelling, and itching at the sting site to a milder generalized reaction. Townsend says horses that are stung typically experience temporary pain and swelling that dissipates within a few hours. Similar to human responses, horses’ individual reactions (e.g., sensitization, reduced immunity) might vary based on previous sting reactions. Anaphylactic shock can occur, but it’s rare.

Options Control paper wasps in the spring, while they are starting their nests, rather than later in the summer. when the colony has grown in size, number, and danger. “Train yourself to look frequently under eaves and sheltered areas for a few weeks in the spring to catch developing nests,” says Townsend. “Only the queen is present then. She can be eliminated with a wasp and hornet spray or swatted with a broom and killed. The nest-building activity lasts for just a few weeks so vigilance should allow you to prevent them from being a potential problem later.”

Remove any animals from the area and treat at night, when wasps are less active. To avoid getting too close to the nests, use an insecticide spray bomb that propels the chemical 12 to 20 feet. Once you’ve treated the nest and wasps are dead, dislodge the nest and destroy it.


These familiar predators come in all shapes and sizes and feed on insects and other arthropods.

Problem “All spiders can bite if accidentally handled or disturbed,” Townsend says. “The puncture wound of all spiders has the potential to become infected.” The toxic bites of black widows and, in some regions, brown recluse spiders, pose particular problems.

Options Reduce spider numbers around the barn and other areas by keeping the barn area clean. If you spot webs, knock them down carefully. Black widows and brown recluses, in particular, do not like to be disturbed, so clean areas regularly and apply a residual insecticide if needed, says Townsend. If these species are present in your region, be particularly careful when picking up items such as bundled blankets, as they like to hide in quiet, undisturbed areas such as these.

Powderpost beetles

These pests are tiny (usually less than 1/4-inch in length) wood-eating beetles and their larvae.

Problem While you might never see them, you are probably familiar with their damage. Powderpost beetles create small, round holes in wood as they tunnel, accumulating sawdust at the openings. They can cause damage in farm structures, from joists and flooring to posts and stall boards. Large infestations can even undermine a barn or building’s structural integrity.

Options Be on the lookout for evidence of powderpost beetles if you are remodeling or renovating old buildings or salvaging lumber from old wooden structures. Farm-sawed lumber is often a source of infestation, note officials with The Ohio State University (OSU) Extension.

If you suspect a powderpost beetle tunnel, dust off the wood surface and wait 24 hours to see whether fresh dust appears around emergence holes. Live beetles or new exit holes indicate activity. Wood no longer infested does not require treatment.

Kiln drying or wood treatments such as paint, varnish, and wax generally eliminate infestations. Larvae already in the wood at the time it is finished with these treatments, however, will still emerge. 

Consider hiring a pest control firm to spray or paint insecticides on infested wood or injecting them into it. If there is an infestation and the wood structure is weakened/compromised, you might have to replace it; if there is a widespread infestation in a structurally sound building, you might need to fumigate it. Check with your local Cooperative Extension System office to identify the pest and determine whether infestations are likely to continue.

Blister beetles

There are thousands of blister beetle species worldwide, but the most common is the black blister beetle.

Problem These beetles contain a defensive chemical called cantharidin that is very toxic to horses, says Townsend. Horses can be poisoned if they touch or consume even a few living or dead beetles in alfalfa hay (beetles present in a field at harvest can be crushed and left in hay that is crimped or conditioned at cutting). Ingesting large numbers of beetles can even lead to death. Unfortunately, it’s almost impossible to detect beetles in hay, and there is no practical way to neutralize or remove them.

Options The blister beetles commonly implicated in poisonings are active after mid-July. Because they are not present at the first late spring cutting of alfalfa, and due to their appetite for weed and alfalfa flowers, manage weeds and time hay cutting to avoid blooming plants. This will greatly reduce the chances of blister beetles contaminating hay at harvest, says Townsend. Also, allowing uncrimped hay to fall before baling will give the beetles a chance to fly away while hay is curing. That way they will not be picked up in bales.


These social insects live in colonies in soil-based nests all over the country.

Problem The worker termites’ main function is to feed the colony. They do this by eating wood, including that of farm -structures.

Options Because termites nest in the ground, you must focus on preventing them from entering a structure. According to Clemson University Cooperative Extension specialists, effective control involves applying a continuous barrier of an appropriate insecticide in the soil between the termite nest and the structure. To complement this chemical barrier, the structure must have been properly constructed to prevent excessive moisture or wood-to-ground contact. If termites are already in the structure, you must re-establish an insecticide barrier and correct any moisture problems and wood-to-ground -contact.

In most cases, it’s best to hire a professional pest control operator with the proper equipment and insecticides to eradicate termite colonies. Officials with OSU Extension suggest that you deal with licensed operators only, get more than one bid, and learn what labeled insecticide will be used, what volume of finished spray will be used, and what warranty is offered.

Take-Home Message

Your best bet when dealing with pests around the farm is to know your potential enemy. As Ferguson suggests, “Learn more about arthropods associated with your horses, and you may prevent them from becoming pests.”


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