The Red Imported Fire Ant (Solenopsis invicta), often referred to as RIFA, is an invasive pest native to South America, known for its painful, venomous sting. Understanding whether this species is present in Utah is important for public health and agriculture, given its capacity to damage crops and ecosystems. This article addresses the current status of RIFA in Utah and details how to distinguish it from native species.
The Current Distribution Status in Utah
The Red Imported Fire Ant is not known to be established in Utah, despite its presence in many southeastern states and isolated pockets in the Southwest and California. Official surveys conducted by the Utah Department of Agriculture and Food (UDAF) have consistently shown a lack of established, self-sustaining populations within the state’s borders. The UDAF views RIFA as a quarantine pest and actively monitors for it, particularly in the warmer, southwestern regions where the climate is considered potentially suitable for long-term establishment.
Distinguishing True Fire Ants from Native Lookalikes
Many large, reddish-colored ants found in Utah are native species frequently mistaken for the invasive fire ant, particularly the Harvester Ant and the Thatching Ant. True Red Imported Fire Ant workers are polymorphic, meaning individuals within a single colony show significant variation in size, ranging from about 1/16 to 1/5 of an inch long. They typically appear reddish-brown with a darker abdomen. A defining structural characteristic is the presence of two distinct nodes between the thorax and the abdomen.
The appearance of the nest is an accurate way to differentiate them from native lookalikes. RIFA constructs a dome-shaped, fluffy mound of soil with no visible central entrance hole on the surface. When disturbed, fire ants swarm out immediately from tunnels located away from the mound’s peak. In contrast, the native Western Harvester Ant (Pogonomyrmex occidentalis) builds a large, flat, circular patch of bare ground often covered with gravel or small pebbles, and features a single, prominent entrance in the center.
Potential Sources of Introduction and Spread
Since the Red Imported Fire Ant is not endemic to Utah, any appearance of the pest is the result of human-assisted transportation from an infested region. Long-distance spread occurs through the movement of materials that can harbor a queen and a small colony, such as live plants, nursery stock, soil, and potted plants shipped from RIFA-quarantined states.
Other regulated commodities that pose a risk include grass sod, hay bales, and bulk landscaping materials. The ants can also be inadvertently transported on vehicles, semi-trucks, or freight originating in the southeastern United States. The UDAF maintains quarantine regulations to intercept these materials, but the constant movement of commercial goods creates a persistent threat for isolated introductions.
Reporting and Management Procedures
If an individual suspects they have found a colony of Red Imported Fire Ants, they must avoid disturbing the mound and immediately contact state officials for identification. Residents should reach out to the Utah Plant Pest Diagnostic Lab (UPPDL) or the Utah Department of Agriculture and Food (UDAF) to report the sighting. Accurate reporting allows for rapid response and containment.
When reporting, provide clear photographs of the ants and the mound structure. Collecting live specimens should only be done with extreme caution, following official guidance. The state recommends against attempting to control or treat the suspected infestation using general pest control methods. Improper treatment can cause the colony to disperse or “bud,” leading to multiple new infestations that complicate eradication efforts.