Argentine ant, Iridomyrmex humilis  It is usually dark-brown/ black. they are between 2 mm to 3 mm long. It usually nests in gardens, around and inside buildings in gardens and even fabric of the building including the roof. The ants forage in trails of many workers around & inside buildings and foundations, and exterior of building.

Are the most common troublesome ants in our experience. They forage for food both inside and outside all types of buildings and are a real pest which usually needs professional treatment. All the nests on a property are often linked and do not destroy other nests.