The vanished plague ants (Hymenoptera: Formicidae) of 19th century Bermuda

Wetterer, J.K.

Abstract: Several 17th and 19th centuries accounts from the Atlantic islands of Bermuda (32° N) describe enormous plagues of ants whose species identities have never been satisfactorily determined. Whereas there are few clues to the identity of the 17th century plague ants, earlier authors proposed four primarily tropical ant species as possible candidates for the 19th century plague ants: Monomorium destructor (Jerdon, 1851), Monomorium pharaonis (Linnaeus, 1758), Pheidole megacephala (Fabricius, 1793), and Solenopsis geminata (Fabricius, 1804). None of these species, however, fit the firsthand accounts very well. Searching the collections of several major museums, I did not find any ant specimens from Bermuda dating from before 1900. However, reanalyzing published accounts, I propose that the 19th century plague ants were a Lasius species. Lasius niger (Linnaeus, 1758) was the only ant species reported from an 1873 expedition to Bermuda, and the first ant from Bermuda identified to species. However, this recorded ant may actually have been some similar Lasius species, e.g., Lasius grandis Forel, 1909, currently the most common ant on the Atlantic islands of Madeira (33° N) and the Azores (37 - 40° N), or Lasius neglectus Van Loon & al., 1990, now a widespread pest species in Europe. Since 1873, no Lasius species has ever again been reported from Bermuda. It is possible that the Lasius of Bermuda were driven extinct by later invading ants. Bermuda's small size, relatively flat topography, and scarcity of intact natural habitat may have afforded the resident Lasius insufficient refuge against the onslaughts of invasive exotic ants.

Myrmecologische Nachrichten 8: 219-224; printable