Distribution of an invasive ant, Myrmica rubra (Hymenoptera: Formicidae), in Maine.

Introduced populations of the north temperate ant species, Myrmica rubra (L.), have become pestiferous in various locations in the northeastern United States, particularly in coastal communities in Maine. Native populations of this ant are widely distributed throughout northern Europe and western Asia; however, nest densities in its native range do not usually reach the high levels observed for many introduced populations. This aggressive ant readily stings, and because of its high densities, homeowners continually encounter nests at a frequency that interferes with use of their properties. Surveys were conducted in Maine from 2001 through 2004 to determine the statewide extent of current infestations. Nests in established populations in coastal Maine were sampled from April through September to assess seasonal changes in the density and composition of colonies. Similarities and differences between introduced populations of M. rubra in Maine and published reports of this species in Europe are discussed. Museum records of this species in North America were also researched and are presented.