Sawfly (Spitfire) Grubs

Perga species

Family: Pergidae

Order: Hymenoptera

Description:

Adult Wasp

Colour - Dock sawfly - Orange body with a metallic blue green back.

Eucalypt sawfly - Brown to black with yellow markings.

Body - Stout. 15-20 mmm long.

Wings - Folded along the body. 2 membranous pairs. Wings are coupled by a series of hooks (hamuli).

The Dock sawfly has transparent bronze with a metallic blue streak at the front.

Mouthparts - Biting and chewing.

Antennae - Elbowed. 5-24 segments.

Legs - Feet (Tarsi) have 5 segments.

Head - Mobile. Large compound eyes.

Thorax - 3 segments attached to segment 1 of the abdomen.

Abdomen - Narrow waist between segments 1 and 2. 9 segments. Spiracles on segments 1 to 8.

Egg - ovoid or sausage shaped

Nymph -

Habits -

Larva

Dock sawfly larva is green with brown spots and a yellow stripe down each side of its body with a brown mouth. Wedge shaped body, 10-15 mm long. and feeds during the day.

Eucalypt sawfly larva or spitfires are yellow, brown to black or steely dark blue and around 25 mm long. Cylindrical body. They are covered with white bristles. When disturbed they raise their tails and exude an odious fluid (made from eucalyptus oils). They are often found in clusters of 20 - 30 during the day and disperse to feed at night.

Head - hard.

Legs - 3 pairs of thoracic legs with 3-5 segments plus abdominal prolegs.

Pupa - silken cocoon.

Biology:

Life Cycle:

Adults are active in spring and summer. They have a saw like ovipositor to split the leaf making a pocket for their eggs. The eggs hatch in autumn and the larva feed on leaves. Dock larva drill holes in pieces of wood to pupate. Up to three generations per year may occur. Eucalypt sawfly pupate in papery cocoons in the ground. It may be several years before the adults emerge from these cocoons. Willow sawfly tend to defoliate Willows over summer.

Habitats:

Origin and History:

Distribution:

Significance:

Larvae feed on the foliage of eucalypts, docks and Willows. Reduction in tree growth may occur but deaths are rare. On dock the sawfly may eat all the leaves on the dock plant but provides little control of this weed. They do not eat other pasture plants.

Management and Control:

In most years control is not economical and in the case of dock sawfly probably not desirable. Clusters of grubs can be removed during the day on valuable trees or trunks can be injected with insecticide.

For stem injection, mix 10 mL dimethoate400 with 10 mL water. Drill 12 mm diameter holes angled downwards at 45 degrees about 25 mm deep into the sapwood at 100 mm spacings around the trunk and about 250 mm above ground level. Inject 3 mL of the dimethoate mix into each hole. Plug the holes with putty a few hours later to prevent decay.

Related Species:

Similar Species:

References:

CSIRO. The Insects of Australia. Melbourne University Press. (1991) p917-926.

WADA. Insects and Allied Pests of Extensive Farming. Department of Agriculture - Western Australia Bulletin No. 4185. p44.

Acknowledgments:

Collated by HerbiGuide. Phone 08 98444064 or www.herbiguide.com.au for more information.