Iridomyrmex humilis (Mayr, 1868) Figs. 20,21. Hypoclinea humilis Mayr, 1868:164. Worker. Pale bronze to bronze black with a deep mesosomal constriction giving a waisted effect accentuated by the high propodeum. Length: 2.2-2.8 mm. Queen. Colour as worker; alitrunk enlarged and high relative to width. Length: 4.5 mm. Male. Bronze black; head very small; alitrunk high and arched. Length: 2.5-3 mm. Biology. This species was introduced into Europe from South America and has become an established and notorious pest in the Mediterranean area, developing very populous multi-queened colonies along the coast. It is sometimes brought into North Europe with plant materials and occasionally colonises heated premises. It does not appear to be able to establish outside in northern latitudes but is present and said to be increasing in the Channel Islands.

Published as part of Collingwood, C. A., 1979, The Formicidae (Hymenoptera) of Fennoscandia and Denmark., pp. 1-174 in Fauna Entomologica Scandinavica 8 on page 33, DOI: 10.5281/zenodo.26691