Notes on the Argentine Ant and other exotic ants introduced into Australia

Abstract

Iridomyrmex humilis [Linepithema humile], Mayr, which was first recorded in the district of Melbourne in September 1939 [cf. R.A.E., A 28 443] but had probably been present for some years previously, now occurs at a number of widely separated points in this neighbourhood in comparatively small but rapidly developing infestations, and drastic measures will be necessary to exterminate the nests already in existence and prevent the dispersion of the ant, which has caused much annoyance in houses [cf. 29 332] and may become a serious pest to farmers, fruit-growers, poultry-men and bee-keepers. A study of its distribution round Melbourne suggests that it spreads by division of a large nest, the workers and females travelling considerable distances; it is dispersed by the carriage of plants, firewood and similar material. Nests have been found in the ground, at the foot of fence posts, under bark or in holes in trees, in the brickwork of houses and walls and in flowerpots; one nest approximately 180 ft. long by a fence contained 37 females in a section about 18 ins. long and 4 ins. wide. Detailed descriptions and figures are given of the worker, female and male of I. humilis, together with lists of the ants that have been introduced into Australia, showing their present known distribution there and the probable country of their origin, and of ants that are not present in the area invaded by I. humilis but occur in the immediate neighbourhood; four indigenous species of iridomyrmex that were common in this area have been displaced.