Suborder Symphyta
Order Hymenoptera
Sawflies are placed in the same order of insects as ants, bees and wasps (Order Hymenoptera). However, they are placed in a separate suborder, Symphyta (ants, bees and wasps belong to the suborder Apocrita) based on reproductive and other characteristics. For example, they do not posses the distinctive thin waist of the other hymenopterans, nor do they possess a sting.
The sawfly's name comes from its ovipositor (or egg laying tube), which is saw-like. The female sawfly uses this ovipositor to saw a slit in plant leaves and stems, into which she then lays her eggs. Sawfly larvae feed mainly on native trees and shrubs, although a small number of species are parasitic.
Larvae of sawfly species that feed upon eucalypts are often seen during the day in large closely packed groups on branches or on the ground. These larvae can cause extensive damage to their food plants. One very destructive genus is the Steel-Blue Sawfly (Perga sp.) which attacks eucalypts in south-eastern Australia.
Sawfly larvae secrete an irritating or distasteful liquid from their mouths. With this defence, the sawfly larvae are usually avoided by predators. The larvae then pupate in a cocoon in the leaf litter. The adult sawfly is usually a dark metallic blue, with a white spot on the thorax, and has a wingspan of about 4cm.
Sawflies are also found on Paperbarks (Melaleuca). A commonly occurring species is Pterygophorus facielongus, sometimes called the Long-tailed Sawfly. Unlike Steel-blue Sawflies, Long-tailed Sawfly larvae do not cluster in large numbers, but may sometimes cluster in small groups in the daytime. One of their favourite food plants is Melaleuca armillaris. At first the small larvae skeletonise leaves. The larger larvae eat whole leaves and can strip all the leaves from the top of the crown, feeding during both day and night. When the Long-tailed Sawfly larvae have finished feeding, they enter a mobile pre-pupal stage, seeking soft bark (such as a paperbark trunk) or soft timber in which to bore and pupate.
The Bottlebrush Sawfly is another species of Pterygophorus, P. cinctus, which feeds on Bottlebrush (Callistemon). Bottlebrush Sawflies pupate without a cocoon in leaf litter. The adult has an orange and black banded body, with a wingspan of about 2cm. Males have feathery (pectinate) antennae.
Adult sawflies are not capable of stinging. However, the larvae may secrete an irritating liquid onto the skin or into eyes if disturbed.
Copyright © Australian Museum, 2003
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