Fire ants may be hitching rides in imported hay

Published: May 17, 2018

Source: USDA APHIS PPQ - Imported Fire Ant Station , USDA APHIS PPQ, Bugwood.org

Red imported fire ants are an invasive species that were unintentionally introduced to Alabama from South America during the 1940's. Since then, they have established populations in at least 13 states from North Carolina and Florida west to California. Because they are an invasive species, very few predators attack them in the United States, and thus, they experience increased population growth and greater abundance in introduced regions compared with their native range.

Fire ants are voracious predators that attack native insects, birds, reptiles, and small mammals. When disturbed, fire ants will defend themselves against larger mammals, including humans and livestock, with a painful sting. Their venom contains formic acid, creating a blister like appearance and intense burning/itching in humans. Even worse, fire ants release an alarm pheromone when they are disturbed, encouraging their nest mates to also attack. Therefore people usually receive multiple stings. Hypersensitivity to fire ant stings requiring medical attentions, occurs in less than 1% of people.

Because fire ants are from the tropics, they are unable to survive Missouri winters. However, because of a cold dry spring, Missouri will likely experience a hay shortage, requiring imports from southern states. Bales of hay from southern states can harbor fire ants, as they have in past years. Hay being shipped to states outside the quarantined area need to be inspected and certified by USDA or state regulatory officials. The certification needs to be available to the buyer. Additionally, buyers should visually inspect each hay bail for fire ants. Attractive baits such as hot dogs or peanut butter can be placed next to bails for an hour then scouted for fire ants. If ants are detected in hay arriving from southern states, several specimens should be collected and university extension officials contacted.

Red imported fire ants are 1/8-1/4 inch long. They can be distinguished from other ants by a two segmented petiole (or waist), and 10 segmented antenna, ending in a two-segmented club. Fire ants are reddish brown in color and have a distinctive stinger at the tip of the abdomen.

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