Black wasp, 20-25mm long, with iridescent blue wings. Legs covered in short bristles. Male wasps are more slender and have longer antennae.
Mainland eastern Australia, in open bushland and suburban gardens.
These wasps do not make a communal nest, but often form small swarms over an area of turf, a compost heap or around a shrub. They can also been seen taking nectar at flowers. The females burrow into the soil to locate scarab beetle grubs, which they sting and lay an egg on; the resulting wasp larva consumes the scarab, to emerge the next season as an adult wasp.
Females can sting but rarely do, as they are not aggressive. Potentially beneficial as predators of scarab grubs.
Control is not necessary. Ignore them.