Giant female scale insects and bird-of-paradise flies

Introduction

This genus includes some of the largest known scale insects in the world. The males and females look completely different. Males are delicate and exotic insects, whilst females are flightless grub-like insects.

Identification

Males have the front pair of wings well-developed for flying, with the hind pair of wings reduced, so that they look superficially like true flies in the order Diptera. The mouthparts are not functional, so the usual characteristic of the order Hemiptera ("sucking mouthparts") is not visible. Males have long waxy filaments protruding from the tip of their abdomen, and when they fly they resemble dandelion seed heads. The wings and body are often coloured with vivid violet or red.

Adult females are large, up to 40mm long, often covered in waxy powder, and are usually found immobile and attached to vertical surfaces such as trees and fence posts.

Habitat

Mostly in sandy heathland, mallee and dry sclerophyll woodland

Distribution

Most of Australia, including Tasmania.

Seasonality

Adults are active from January to June.

Feeding and diet

Immature stages live underground on roots of plant hosts where they suck sap. Food plants are poorly known, as adult females often move away from nymphal feeding locations.

Life history cycle

Females moult into the adult stage and crawl up above ground and onto vertical structures such as trees and fence posts. Males mate with the females at this stage, then the females crawl to a protected place such as under bark, or in a crevice, where they become immobile and appear essentially dead. At this stage the four posterior segments of the abdomen are retracted into the abdomen to form a large cavity ("marsupium"), with a posterior slit-like opening. The first instar nymphs ("crawlers") develop inside this marsupium in the dead leathery body of the mother, then emerge, dropping onto vegetation and soil. Mortality of these crawlers must be very high as 1,000 to 2,000 are produced per female.