Nile Virus Guidelines for Horse Owners
Mosquitoes, like other biting flies, can cause serious annoyance and stress
to horses. Mosquitoes also can transmit disease-causing organisms, such
as the West Nile Virus. The following guidelines are provided to reduce
mosquito habitat and limit exposure of horses to biting mosquitoes.
Adult mosquitoes are feeders of blood. Mosquitoes require blood meals to complete
their development. Generally, mosquitoes in our area feed during or between
dusk and dawn. However, some species can feed during the day. Be aware of mosquito
activity on your property/farm. Select the following preventative methods for
protecting your horse.
horses for West Nile Virus. West Nile Virus vaccination program
for horses is available at your local veterinary office. Currently,
this vaccination requires two treatments, three to six weeks
apart with an annual booster shot. Vaccinate your horses at least
three weeks prior to mosquito season to ensure that your horse
will be protected.
horses inside during hours of mosquito activity. Be sure that
the enclosure is screened properly to prevent mosquitoes from
check for adult mosquitoes in enclosures. To reduce adult mosquitoes
in the stable, treat the area with an insecticide registered
for that specific use and that is effective on adult mosquitoes.
Be sure to read and follow the pesticide label. Use pesticides
only when adults are present; do not use pesticides as a preventative
fans to reduce mosquito feeding inside stables. Creating wind
drafts can potentially reduce mosquitoes’ ability to feed
electrical lighting during nighttime hours in horse enclosures.
Mosquitoes can be attracted to light.
domesticated fowl to areas away from horse stables. Mosquitoes
that transmit WNV are attracted to birds.
repellents can be used to deter mosquitoes. Read and follow the
label when using these repellents.
repellents that emit high frequency sounds do not repel mosquitoes,
or other pests. Additionally, electronic bug zappers do not control
mosquitoes or other flying pests. In fact, they work indiscriminately,
killing many beneficial insects that prey on pests.
developed carbon dioxide baited traps do attract and trap many
adult mosquitoes. These traps can be expensive.
Since all mosquitoes require water to complete their lifecycle, managing and
eliminating standing water is key in controlling mosquito populations. The
following guidelines are provided to assist in identifying potential sources
of mosquito problems around the farmyard and pasture.
water-trapping containers and landscapes:
dispose of, or recycle cans, plastic buckets or other water-trapping
un-mounted tires in a manner to prevent rainwater collection.
tight covers or screens over cisterns, fire barrels, rain barrels,
tubs, septic tanks and other water collectors.
or drain seepage ponds and puddles.
or fill low areas to prevent standing water.
and repair leaky irrigation systems, pipes and faucets.
avoid puddles, do not over-water lawn and garden.
drain or manage water-trapping containers and bodies of water:
drain and scrub watering troughs and animal dishes. These should
be maintained at least two times per week during warmer summer
and scrub rain barrels every week (more frequently during summer).
clean and repair gutters to prevent standing water inside gutters.
check and drain plastic covers and tarps used outside.
water-trapping containers such as wheelbarrows and buckets upside
down or inside shelters.
weeds; keep vegetation short around water. Adult mosquitoes are
attracted to dense, tall vegetation around water.
unnecessary floating structures or debris from ponds. Mosquitoes
are often found around floating debris.
drains, ditches and culverts clean to allow proper drainage.
stocking ornamental or permanent, self-contained ponds or watering
troughs with insect-eating fish, such as goldfish.
pond edges to a shelf or steep slope. Mosquitoes prefer shallow
Pesticides to Control Mosquitoes
Insecticides registered for adult mosquito control may be used inside horse
enclosures. Be sure to read and follow the label directions. Using insecticides
to kill mosquito larva around the home is not recommended as the only control
method. Due to concerns about pesticide contamination of surface water, many
restrictions apply in Washington State. According to current Washington state
law, only a few pesticides are available for use in contained water bodies
by homeowners without a Washington State Department of Agriculture pesticide
license. Individual landowner insecticide management of mosquitoes is rarely
effective; management for mosquitoes is best achieved as a regional/municipal
effort. Contact your local government for mosquito abatement information. Consult
WSU Pest Leaflet Series "Pest Management for Prevention and Control of
Mosquitoes" PLS 121 (http://pep.wsu.edu/pdf/PLS121mosquito.pdf)
for more information.
College of Veterinary Medicine
State Department of Agriculture
Veterinary Medical Association
Waste Lagoons to Control Mosquito Breeding
more information contact your local extension
WSU Extension- Whatcom County
1000 N. Forest St., Suite 201
Bellingham, WA 98225
this fact sheet...