Fire Ant Surveillance for Horse Farms

Fire Ant Surveillance for Horse Farms

The red imported fire ant is red to brown with a black abdomen.

Photo: Sanford Porter/USDA Agricultural Research Service

The red imported fire ant can be found in parts or all of Alabama, Arkansas, California, Florida, Georgia, Louisiana, Mississippi, New Mexico, North Carolina, Oklahoma, Puerto Rico, South Carolina, Tennessee, Texas, and Virginia (see Figure 1 below). Occasionally, it has been found in Kentucky, Maryland, and Missouri. Fire ants like to establish colonies in open sunny fields and pastures. Soil moisture and winter temperatures round out the major environmental factors that limit the spread of this invasive insect. Changes in climate, along with the adaptability of the insect, point to a continued gradual expansion of its boundaries.

The impact of the fire ant extends beyond the pain of its legendary sting. No significant adverse effects to the health of foals or mature horses have been reported in states in which fire ants are widely established. But, in addition to causing injury to workers, animals, and wildlife, this small insect affects pasture maintenance, hay production, damages equipment, and increases costs. Horse-farm managers in fire ant-infested areas have adjusted their management practices and developed strategies to live with this pest.

The gradual northward and westward expansion of the fire ant’s range exposes more farm managers and stable and pleasure horse owners to this important pest. Those living along the expansion front should become familiar with some of the basics of fire ants and watch for ant activity that seems out of the ordinary.

The familiar mound is the ant’s hallmark, but there is one major difference when it comes to fire ants: Their mound is the typical pile of loose, fine soil but there is no central opening. Instead, fire ants enter and leave their colonies through underground tunnels that radiate from the mound. Mound heights range from a few inches in mowed areas to 18 inches in undisturbed areas. Repair of a fire ant mound collapsed by a heavy rain results in a loose, fluffy pile of soil a few days later.

Fire ants look like typical ants. They are small but vary from 1/8- to 1/4-inch in length. The head, thorax, and legs are red to brown with a black abdomen. Positive identification of fire ants requires collecting approximately a dozen specimens in rubbing alcohol and taking them to your local cooperative Extension office. This must be done carefully. Disturbing the mound usually prompts numerous ants to pour out and climb up any vertical surface to sting the intruder. Other ant species scurry about when the colony is disrupted, working to protect the queen and move their brood to a safe place.

Collect the ants carefully to keep from being stung. Achieve this by dusting baby powder on dishwashing gloves and wearing them because the ants cannot crawl up dusted surfaces. Stay as far away from the mound as possible during collection and watch for ants crawling on your shoes.

Follow up a positive identification of fire ants with a careful examination of the property in spring or late fall to determine the number and location of active mounds. Fire ants are managed by careful application of baits or mound drenches of insecticides labeled for fire-ant control. Take advantage of the excellent information available on fire-ant management.

For more information, see Identifying Fire Ants,

CONTACT: Lee Townsend, MS, PhD——859/257-7455—University of Kentucky Department of Entomology, Lexington

This is an excerpt from Equine Disease Quarterly, funded by underwriters at Lloyd’s, London.

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Equine Disease Quarterly

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