Invasive species pose challenges to ecosystems and human well-being. Among these, certain ant species are concerning due to their aggressive nature and painful stings. The question of whether “fire ants” have established themselves in Oregon is common, reflecting public awareness of their potential impacts. Understanding these ants is important for safeguarding local environments and communities.
The Current Status in Oregon
While the red imported fire ant, Solenopsis invicta, is a major concern in the southeastern United States, it is generally not established in Oregon. This species has been intercepted in Oregon, but its widespread establishment is not yet confirmed. Some entomologists doubt Solenopsis invicta could endure Oregon’s cool, wet winters, though areas like the Willamette Valley might be susceptible. Established Solenopsis invicta populations in California, particularly in nurseries shipping plants to Oregon, remain a pathway for potential introduction.
Instead, the primary “fire ant” species established in parts of Oregon and the Pacific Northwest is the European fire ant, Myrmica rubra. This invasive species, native to Europe and Asia, was first detected in British Columbia in 2010 and has since spread to northwestern U.S. states, including Washington. Myrmica rubra prefers moist environments like lawns, gardens, and waterways, where infestations can be dense. Unlike some other fire ants, European fire ants do not typically form large, visible mounds, instead creating numerous underground nests.
Identifying Fire Ants
Accurately identifying fire ants is an important step in distinguishing them from other ant species common in Oregon. The European fire ant (Myrmica rubra) workers are relatively small, typically measuring between 4 to 5 millimeters in length, with queens being slightly larger, up to 9 millimeters. Their coloration ranges from reddish-brown to a more yellowish-brown, sometimes appearing golden in direct sunlight. A distinguishing physical characteristic is their constricted waist, which consists of two segments, and the presence of two backward-pointing spines on their middle body section.
When their nests are disturbed, these ants are known for their aggressive behavior and tendency to sting readily. The sting of Myrmica rubra is described as painful, often compared to the sensation of stinging nettles, and can cause localized swelling and itching. While typically not severe, some individuals may experience more significant reactions.
Responding to Fire Ant Encounters
If you suspect an encounter with fire ants in Oregon, particularly the European fire ant, taking appropriate steps is important for management and containment. The Oregon Invasive Species Hotline is a resource for reporting suspected invasive species sightings. Reports can be submitted online or by phone, connecting you directly to experts who can assist with identification. Providing detailed information, including the exact location and photographs, helps experts positively identify the species.
Collecting a sample, if it can be done safely, can also aid accurate identification by specialists. Reporting is important for early detection efforts, allowing state authorities like the Oregon Department of Agriculture (ODA) and Oregon State University (OSU) Extension Service to monitor and respond to new infestations. The establishment of invasive ants can lead to various impacts, including ecological disruptions by displacing native ant species and health concerns due to their painful stings. Community vigilance and prompt reporting protect Oregon’s natural resources and public health.