Spitfire sawfly
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Suborder: Symphyta
Family: Pergidae
Genus: Perga
Species:
P. affinis
Binomial name
Perga affinis
Kirby, 1882

The spitfire sawfly (Perga affinis, family Pergidae) is a hymenopteran insect found in Australia. It is up to 22 mm long, has two pairs of wings, with a wingspan up to 40 mm, and its wings are honey colored. Its larvae are up to 80 mm long and somewhat resemble a caterpillar.

The sawfly derives its name from the saw-like ovipositor of the female,[1] which is used to open holes in the plant within which she lays her eggs. While closely related to wasps, sawflies lack both the narrow waists and stings of wasps.

Although the adults of this sawfly species are not often seen, the larvae are quite conspicuous as they grow larger, resembling hairy caterpillars.[2] Steelblue sawfly larvae are usually seen during the day in groups on the branches and stems of Eucalyptus trees. At night, they disperse to eat leaves of the host plants. When threatened, the larvae raise their heads and eject a strong-smelling, yellow-green liquid consisting predominantly of eucalyptus oil, to deter predators.[1] This action gives them their common name of spitfires.

Description

Spitfire sawfly larvae

The larvae vary from dark blue or black to yellow and brown depending on the species, and are up to 80 mm long. The body is sparsely covered with white, bristly hairs. During the day, the larvae congregate in clusters of 20 to 30 for protection and disperse at night to feed. The adult wasps are mainly black or brown, with yellowish markings and are about 25 mm long.

Spitfire caterpillars on concrete footpath, Oct 2012, Bathurst
Spitfire caterpillars on tree trunk, 1 Oct 2012, Forde ACT
Spitfire caterpillars on eucalypt stem, 27 September 2017, Cooyal NSW

Lifecycle

The adults are found from about January to May, though mainly in autumn. Eggs are laid under leaf surfaces with the saw-like ovipositor. The larvae are mainly active during late winter and spring and enter the soil to pupate usually in mid-spring. Pupation takes place in strong. paper-like cocoons, which are often clustered several centimetres deep in the soil. The pupal stage may extend over two or three years before the adult emerges.[3]

Damage

Larvae of spitfires feed on the foliage of young trees and regrowth stems, and can strip the branches of foliage, particularly at the tops. This is usually replaced during the spring-summer flush of leaf growth. Serious retardation of high growth may result from repeated attack, but host death is unusual.[1] Wandoo is the most commonly attacked species in Western Australia.

Control

This defoliator rarely causes widespread damage, but where the clusters of larvae are accessible, the simplest method of control is to remove and destroy them during the day. Several parasitic wasps also have some controlling effect.[1]

References

  1. 1 2 3 4 Charlma (December 1992). "Spitfires - Defoliating Sawflies". PIRSA. Archived from the original on 6 November 2009. Retrieved 2010-04-10.
  2. ↑ Gary, Opit (17 January 2008). "Sawflies and spitfire grubs". abc.net.au. Retrieved 10 April 2010.
  3. ↑ http://www.pestanators.com/Pest-Identification.html
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