Monomorium

Species of Monomorium are very diverse in size and habits, ranging from very small generalist scavengers to large, polymorphic seed harvesters. It is especially diverse in the Old World with only a handful of species in North America, some of them tramps introduced from other areas. Nests vary from small colonies under rocks to large, low mounds, and a few species nest arboreally under bark or in rotten wood either on trees or on the ground. Many species form small mounds in open soil which are highly visible because of the large number of workers foraging in its vicinity. Colonies contain multiple queens (are polgynous) and often consist of a series of individual nests (are polydomous). A few species are inquilines in the nests of related species while others have wingless (apterous) queens or have both wingless and winged (alate) queens. Foraging is primarily during the day, with some species limited to the hotter periods. Some species, especially those introduced through human activity, can be significant pests as they forage in houses and buildings.



Worker of M. aithoderum from South Australia.



Worker of M. whitei from New South Wales.

Identification
The antennae have 10 to 12 segments (including the scape) and a 3 segmented club. The front margin of the clypeus just above the mandibles has a single central elongate hair or seta. The upper surface of the head is smooth and lacks grooves or depressions to receive the antennal scapes. The petiole, and generally the postpetiole, with distinct, arched nodes on their upper surfaces. All workers in a nest can be approximately the same size (monomorphic) or vary greatly in size (polymorphic).

This large and diverse genus can be separated from other Australian ants by the central hair or seta on the front margin of the clypeus, the 3-segmented antennal club and the arched nodes on the petiole and postpetiole.

Distribution and Habitats
Australian distribution

Regional Species Lists

 * Australia

Keys to Species

 * Australia