Omnivorous Insect a Risk to Humans, Animals, and the Nursery Industry

Photo: Eli Sarnat, PIAkey: Invasive Ants of the Pacific Islands, USDA APHIS ITP,

ANNAPOLIS, MD (August 4, 2003) – With a bite hotter than the southern summer, the omnivorous Red imported fire ant, Solenopsis invicta, is the state’s most recent invasive species of the month. Since the first detection of the insect in Maryland in 1986, it has been intercepted by aggressive surveillance and eradication efforts of the Maryland Department of Agriculture, preventing its establishment in the state. As with many invasive species, the department relies on reports from residents to detect new infestations.

This South American native ant probably first came to North America as an unwanted passenger on cargo ships coming into the port of Mobile, Alabama, in the late 1930’s. Since then, the ant has slowly spread north, both by natural migratory movement and through human activity, such as the interstate transport of nursery stock and other agricultural commodities. Currently, 320 million acres of the southern United States are generally infested, requiring the Federal quarantine in 13 states and Puerto Rico.

This ant is small, but makes up for its diminutive stature with aggressive behavior when defending its nest and a nasty sting. Fire ants are omnivorous, attacking and occasionally killing newborn domestic animals as well as pets and wildlife. It also feeds on buds and fruits of almost any plant. In the 13 southern states where it is present, the ant has had a severe impact on ground nesting animals ranging from other insects to birds and mammals. In agriculture, fire ants have damaged numerous cultivated plants including corn, sorghum and soybeans.

In urban areas, infestations of the imported fire ant have an impact on outdoor activities, threatening small children, those allergic to insect venom, and the elderly. A single fire ant will sting multiple times, resulting in a painful burning sensation (thus the name ‘fire’ ant). This is then followed by the formation of white blisters or pustules. These blisters can become infected if not cared for properly.

The Maryland Department of Agriculture Plant Protection and Weed Management Section staff, through inspection and survey efforts, have made many interceptions and detections since 1989 and only aggressive eradication efforts have prevented the establishment of this pest in the state. Support from the USDA Plant Protection and Quarantine Program has allowed intensive survey activity in Maryland that has identified colonies from Ocean City to Frederick, allowing timely treatments to eradicate this pest.

MISC hopes to raise public awareness about the problems with this and other invasive species through its “Invader of the Month” program. For more information or to report possible fire ant activity, contact the Maryland Department of Agriculture Plant Protection and Weed Management Section at 410-841-5920.