Some aspects of the biology of the mound ant Iridomyrmex Detectus (Smith)

Abstract

Counts of foragers of Iridomyrmex detectus (Smith) leaving the nest during the day revealed, over a 4-month period, bimodal diurnal activity patterns under natural conditions. It is likely that the patterns are basically endogenous, modified by environmental factors. The number of ants active in a foraging trail at any time decreases with distance from nest and the trails are often impermanent, though some lasted almost unchanged for 4 months. Nests were made from excavated earth and capped with a variety of materials. The behaviour on the nest surface mostly consisted of apparently random wandering which sometimes resulted in the ant leaving the nest, and sometimes its return to its hole of emergence or to another hole. The uncoordinated behaviour of the ants when the nest is molested and the inefficient way in which they handle objects and carry food and building materials, are suggestive of an unspecialized type of behaviour life. Attempts to reverse the orientation of the ants have shown how difficult this is and the possibility that smell and sight govern orientation has been discussed. Territoriality among nests is described together with a phenomenon of "common trails," thought to represent still-existing links between parent and "branch" nests.