Perga and related genera

Family: Pergidae

Order: Hymenoptera

Identification:

Tightly packed clusters of larvae (spitfires) clinging to stems or branches of gum trees during the day. Larvae of Steelblue and Large Green Sawflies are black and covered in short white hairs. Other species are differently coloured. Adults (sawflies) are rarely seen, but resemble large, stocky wasps; they frequent foliage of host plants.

Distribution:

On eucalypts in Tasmania and much of mainland Australia.

Life history:

Female sawfly inserts her eggs into the leaf using her "saw". On hatching, larvae feed together on leaf edge, later forming clusters by day and feeding by night. Hungry larvae will migrate en masse to another tree if they strip the first one. Upon maturing, they descend from the tree and bury themselves in the ground to pupate. Adult sawflies later emerge from the soil.

Pest Status:

Spitfires commonly defoliate young eucalypts. Otherwise they are harmless, likewise the adult sawflies, which cannot sting although they are related to wasps.

Management:

Spitfires will have little overall effect on larger trees and can be ignored. On saplings and smaller trees, clusters of larvae can be knocked or washed off or removed by hand and killed. Otherwise, a registered sawfly insecticide (with wetting agent) can be applied directly to the larvae. Do not spray whole trees as this kills many beneficial insects, including sawfly parasites.