[6] F. pratensis can reach a length of 4.5–9.5 mm (0.18–0.37 in) in workers, slightly larger than in other species such as the more common southern wood ant F. rufa or F. polyctena.Their nests are built from grasses, pine needles and straw, and can reach up to a meter in diameter.[7][8] Winged males and females can be present in nests from late April to September, as this species reflects the production of two separate generations.This species can be found in Austria, Belgium, Bulgaria, Czech Republic, Estonia, Finland, France, Georgia, Germany, Guernsey, Hungary, Italy, Latvia, Lithuania, Luxembourg, Moldova, Netherlands, Norway, Poland, Romania, Russia, Serbia and Montenegro, Slovakia, Spain, Sweden, Switzerland, Turkey, and Ukraine.[11][12] In forests weakened by pollution and acid rain in central Europe, red wood ant populations are often endangered for little known reasons which in turn causes further imbalances in predator-prey dynamics and the ecosystem.