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Pest NameDescription 
European fire antEuropean fire antThe European fire ant (<i>Myrmica rubra</i>), sometimes known as the red ant or ruby ant, is a native of Europe and Asia. It has been present in the northeastern United States and neighboring Canadian provinces for many years, and has also been found recently in Washington State and British Columbia. While its occurrence in the Pacific Northwest is relatively isolated for now, it has great potential to spread and become a significant pest in our area. European fire ant (EFA) workers are reddish-brown ants about 1/5 inch long. However, color can vary greatly between individuals and between colonies. The body is covered with fine hairs. The head and thorax are sculpted with ridges and grooves and appear somewhat dull, while the abdomen is shiny. EFA workers have two backward-pointing spines on the back of the thorax and a distinct, two-segmented pedicel or “waist.” This species does not build obvious mounds or hills. They like high humidity so will often build in soil at the base of trees or shrubs, under rocks or logs, or in similar sheltered or shady areas. Some colonies have been reported to move nests regularly during the summer. EFA colonies contain multiple queens and may spread into adjacent areas by “budding” (forming satellite colonies of a queen and a group of workers). They are typically spread by transport of infested container plants, soil, or mulch. EFA is considered a potentially significant pest species due to the highly aggressive nature of the workers, the high population density in infested areas, and its fondness for nesting in areas also enjoyed by humans. EFA workers can deliver a painful sting which may cause severe allergic reaction including anaphylactic shock in sensitive individuals. In addition to human impact, these ants will also have an effect on the ecology of the areas they invade, both by impacting native species and by their habit of tending and protecting aphids and other honeydew-producing plant pests. European fire ant should not be confused with the two imported fire ant species (<i>Solenopsis</i> spp.) that are a problem in the southern United States. For assistance identifying suspected EFA specimens, contact your local Extension office.