Imported fire ants, known for their aggressive nature and significant threat in warmer climates, are generally not established in Colorado. These ants, primarily the red imported fire ant (Solenopsis invicta), thrive in environmental conditions different from those typically found across the state. Understanding the factors that limit their presence, along with proper identification, helps addressing any suspicions.
Fire Ant Presence in Colorado
The invasive red imported fire ant (Solenopsis invicta) and black imported fire ant (Solenopsis richteri) are not established in Colorado. These species are native to South America and are primarily found across the southern United States, including states like Texas, Florida, and Alabama. While isolated instances of transport into Colorado via goods or nursery stock occur, they typically do not form established, reproducing colonies. Instead, many native ant species in Colorado, such as the red harvester ant (Pogonomyrmex barbatus), are sometimes mistakenly identified as fire ants due to their reddish coloration or painful stings. Red harvester ants are a common native species in Colorado, known for their distinct mounds and potent sting, which can be more painful than a fire ant’s.
Environmental Factors Limiting Fire Ant Spread
Colorado’s climate presents significant environmental challenges that prevent the establishment of invasive fire ant populations. These ants are adapted to warm, humid, subtropical conditions, which are not typical of most of Colorado. Cold winter temperatures, high elevations, and arid conditions create an unfavorable habitat for their survival and reproduction. Prolonged exposure to cold temperatures limits the ability of fire ant queens to produce new alates (winged reproductive ants) and can cause freeze-kills, thereby hindering colony expansion. The minimum temperatures in many parts of Colorado are too low for these invasive species to thrive and establish widespread colonies.
Identifying and Reporting Suspected Fire Ants
Proper identification is important if you suspect fire ants, as many native ant species can sting or build mounds. Invasive fire ants are typically reddish-brown with a darker abdomen, and their workers vary in size within a single colony, ranging from 1/8 to 1/4 inch long. A distinctive feature is their two-segmented petiole, appearing as two small bumps between the thorax and abdomen, and they possess elbowed antennae. Their mounds are often dome-shaped, lack a central opening, and can become quite large. If disturbed, fire ants exhibit aggressive behavior, swarming quickly and stinging repeatedly.
If you encounter ants you suspect are invasive fire ants, avoid disturbing the nest to prevent stings and further dispersal. Take clear photographs or videos of the ants and their mound, noting the exact location. Contacting a local expert, such as your county’s Colorado State University Extension office, is the recommended next step for proper identification and guidance. They can provide accurate information and advise on any necessary actions, ensuring that native species are not mistakenly targeted.