This month, imported fire ant colonies have been confirmed and treated in two Kentucky counties: Marshall and McCreary counties. While we have had other colonies in Marshall County, this is the first instance of fire ants in McCreary County. Management of imported fire ants relies on people quickly reporting suspected fire ant nests (mounds). Kentucky entomologists will confirm if they are fire ants. If confirmed, the colonies will be treated and killed so that Kentucky does not become an area requiring the establishment of quarantines.
Early spring is a great time to looks for fire ant mounds as there is less weed cover to hide the mounds, and the fire ants build higher mounds in the winter. During cool, wet periods, the workers will build the mound high above the soil, so they can keep the brood warm with more sunlight exposure and provide better drainage when the soils are saturated. We have noticed in Kentucky that the nests are typically in open sunny areas or on south-facing slopes for warmth. During hot, dry periods, the ants tend to stay deeper in the soil, so they can keep the brood cool and moist; even large colonies may not be visible above the grass.
Fire ants can have as many 100,000 to 500,000 workers in a colony. The raised soil nest is fiercely defended by sterile workers. Nests may be found in urban areas, agricultural areas, pastures, or grasslands.
Imported fire ants continue to move northward. Last year, the Tennessee Department of Agriculture expanded the number of counties under imported fire ant (IFA) quarantine. Several of the newly quarantined counties are now on the Kentucky border. IFA colonies have periodically been found in the Purchase Area of Kentucky, mostly in the Land Between the Lakes region between Lake Barkley and Kentucky Lake. Thus far, Kentucky has been able to avoid an IFA quarantine by treating and killing individual colonies and not allowing IFA to become established in those areas.
Fire Ant Species & Introduction to U.S.
The red imported fire ant (RIFA), Solenopsis invicta, is native to South America and was first found in the U.S. in the 1940s. It spread from the initial introductions and is common throughout much of the Southern U.S. A second species, the black imported fire ant (BIFA), Solenopsis richteri, was introduced into Mobile, Ala., in 1918 and has a smaller distribution; it has been found in parts of Mississippi, Alabama, Tennessee, Virginia, South Carolina, and Arkansas. BIFA is more cold-tolerant than RIFA and has been found established further north. Most of the mounds treated in Kentucky have been identified as BIFA; however, RIFA has also been identified. These two species can also hybridize in areas where they both occur. The hybrid may be even more cold tolerant.
Injury to Humans, Animals & Crops
Both species have a painful sting that results in a light-colored blister with a reddened area encircling the blister. They clamp on with their powerful jaws and sting victims repeatedly. The reason they are called fire ants is because their venom causes a burning sensation. In sensitive persons, the sting can result in anaphylactic shock. There are some reports that the sting of BIFA is more pronounced than that of RIFA. Besides attacking people, fire ants can attack and sting pets and wildlife. They can also damage seedling corn and soybeans.
Spread
While fire ants can spread locally through their normal mating and dispersal process, they can travel longer distances by hitchhiking in hay, nursery stock, or any plants with roots and soil attached, soil-moving equipment, RVs and other motor vehicles, and in sand, gravel, grass, sod, or wood. For that reason, the USDA APHIS limits the spread of fire ants by quarantine. They limit the spread of fire ants by requiring inspection and specific treatments for nursery stock, turf, and baled hay and straw that have been stored in contact with soil. They also regulate the movement of soil and soil-moving equipment out of quarantine areas.
Treatment Strategy
The strategy for Kentucky is to identify IFA mounds and treat them as soon as possible so that they don't spread and do not become established. We need people, particularly in southern Kentucky counties along the Tennessee border, to be on the watch for fire ants. The best way to locate fire ants is by visually searching for the raised mounds. If a suspected fire ant mound is found, people should contact their local county Extension office to report the sighting. County agents need to report sightings to the Office of the State Entomologist here at UK.
Categories: Kentucky, General