The hatchet or flag wasps are a small family of wasps with around 40 species.
Hatchet wasps have a long thin waist and a flat abdomen that moves up and down as they walk, resembling a flag or hatchet.
Hatchet wasps live in urban areas, forests and woodlands, arid areas and grasslands.
Hatchet wasps are found throughout Australia.
Life history cycle
Hatchet wasps parasitise the egg cases of cockroaches. The female wasp searches for recently laid cockroach eggs on which to lay her own. The wasp larvae hatch first and eat the cockroach eggs, eventually pupating to become fully developed adults.
One introduced species of hatchet wasp, Evania appendigaster, is common in Sydney and is extremely welcome because it parasitises the American Cockroach (Periplaneta americana), an introduced pest. Having eaten their fill, the larvae pupate into fully developed adults.