While fire ants are a significant concern in many parts of the United States, Iowans can rest assured that these stinging insects are not established as a widespread, reproducing population within the state. Understanding why they are absent from Iowa and how accidental introductions can occur helps maintain this status. This knowledge helps residents identify potential risks and prevent these invasive ants from gaining a foothold.
What Are Fire Ants?
Fire ants, particularly the red imported fire ant (Solenopsis invicta), are small, aggressive insects that originated in South America. They measure between 1/8 to 1/4 inch in length and have a reddish-brown body with a darker abdomen. These ants build characteristic dome-shaped mounds of loose soil, which can grow quite large, sometimes reaching 18 to 24 inches in height. Unlike many other ant species, fire ant mounds often lack a clear central opening.
When disturbed, fire ants respond with aggression, swarming rapidly and stinging repeatedly. Their sting is painful, causing a burning sensation followed by the development of itchy red welts and pustules on the skin. These insects prefer open, sunny environments such as lawns, pastures, and fields. The red imported fire ant was first accidentally introduced to the United States through the port of Mobile, Alabama, around the 1930s, likely in soil used as ship ballast.
The Current Status in Iowa
Despite their widespread presence across the southern United States, fire ants are not established in Iowa. The primary reason for their absence is Iowa’s climate, which includes cold winters that are inhospitable to these warmth-loving insects. Fire ant colonies struggle to survive extended periods when soil temperatures freeze deeply. While fire ants can tolerate below-freezing temperatures for short durations, sustained cold below 10 degrees Fahrenheit significantly impacts their populations.
Individual fire ants or small, isolated colonies might occasionally be transported into Iowa. This occurs as “hitchhikers” on items moved from infested regions, such as nursery plants, sod, landscaping materials, or even used outdoor equipment. However, these transported colonies do not survive the state’s harsh winter conditions long enough to establish widespread, reproducing populations. State agencies monitor for invasive species to prevent such establishments.
Preventing Fire Ant Introduction
Preventing the accidental introduction of fire ants into Iowa depends on public awareness and vigilance. These ants often enter new areas through materials moved from established states. This includes purchasing potted plants, trees, shrubs, or sod from southern regions. Carefully inspecting the soil and root balls of such plant materials before bringing them into Iowa can help prevent hidden ant colonies.
Similarly, used outdoor equipment, such as lawnmowers, trailers, or recreational vehicles, that has been stored or used in fire ant-infested areas could harbor ants or even small colonies. Cleaning and inspecting these items thoroughly before transport can mitigate this risk. If any suspicious ants or mounds are discovered, it is important to report them to local agricultural extension offices or state authorities. Early detection allows for prompt action to prevent potential establishment and spread.