Prolasius advenus

Prolasius advenus is a species of ant in the genus Prolasius. It is endemic to New Zealand, where it is widespread across the North and South Islands, including offshore islands. P. advenus typically occurs in forest habitat, but can also sometimes be found in open habitats such as tussocks. It was first formally described in 1862 by Frederick Smith from a specimen collected in Lyttelton. It is commonly referred to as the "small brown bush ant". The ant is small and coloured brown, with workers being 2.9–3.5 mm in length. Colonies typically have hundreds of workers and several queens. It is a generalist forager that scavenges for food. When starved of food, it becomes more aggressive towards other ant species. Unlike some other ant species, the worker is not sterile and can produce male offspring if the queen is absent. Several species of beetle, such as Holloceratognathus passaliformis and Neosampa granulata, live in the nests. P. advenus is impacted by high densities of Vespula wasps, which cause genetic bottlenecks and result in the worker having a smaller body size.