Ecology and general biology of five sympatric species of Myrmecia (Hymenoptera : Formicidae).

Five sympatric species of Myrmecia were studied within a small isolated mallee area near Bacchus Marsh Victoria. The general biology of each species was investigated and an attempt made to determine any ecological differences by which direct interspecific competition was avoided. The social organization of each species was also examined using colonies maintained in the laboratory.The external nest structure of each species was distinctive whereas the internal nest structure was similar in all species except in M. nigriscapa which was more complex. Migration of nests to new sites occurred in two species, M· forceps and M· nigriscapa.Foraging was primarily nocturnal in four of the species and one of these, M· pyriformis, appeared entirely nocturnal. The remaining species, M. nigriscapa, had a highly variable foraging pattern, foraging whenever the temperature was favourable. Variation in the number of ants foraging at different times of the year was measured in each of the species; this correlated closely with the brood in the nest. M· pyriformis which carried a large number of larvae over winter, foraged more than the other species in this season. M· nigriscapa, had no brood in winter and ceased all activity. This absence of a winter brood was due to the restriction of the oviposition period in M· nigriscapa to the period around spring from mid-July to early December. Oviposition occurred throughout the year in the other species.[...]