Nature Notes: the defence of spitfire grubs

These grubs are commonly called spitfires.

That name comes from the mustard-coloured, eucalyptus-smelling thick liquid they exude from their mouths when disturbed. They raise their heads at the same time.

Most observations of these grubs involve a cluster. This is their usual daytime position.

At night they spread out to feed alone. Then, as daytime approaches, they somehow regroup together in their protective cluster.

They probably communicate by tapping vibrations they make on the twigs and branches.

Spitfires have few enemies. A few birds sample them from time to time, but none seem to relish them. The grubs no doubt have a strong taste of eucalyptus.

Most sightings of spitfire grubs are on eucalypts that have been planted. They seem to use local indigenous trees much less frequently. Leaves at the top of the host tree are consumed first. The grubs then gradually make their way down. Damage can be serious, sometimes leading to complete defoliation. However, most trees will resprout after the grubs have departed.

The adult sawflies look like wasps and are seldom seen.

They get their name from the saw-like egg-placer the female uses to lay her eggs in eucalypt leaves.

The caterpillars eventually move down the tree to pupate in the soil. This takes places in mid-spring.

The photo shows a cluster of average size. On a large tree, several clusters may merge. On rare occasions there may be thousands in the one huge ugly mass.

Revegetation birds

A COUPLE of months ago we mentioned a local Landcare group having the satisfying sight of a koala in a manna gum tree they had planted a relatively short time before.

Two somewhat similar sightings have occurred recently.

The first is a small group of white-winged choughs in a planted area on the west side of Lake Burrumbeet. The trees and shrubs at that spot were planted 29 years ago.

Growth there has not been rapid, but the plants have grown sufficiently to make a rather natural-looking environment.

White-winged choughs feed on the ground, where they scratch among leaf litter. The planting has now produced sufficient litter - and associated invertebrate food - to attract them there.

The arrival of such birds indicates that the planting has been very successful. Choughs are unlikely to visit a young planted area dominated by pasture grasses - as this spot once was.

The second recent report concerns an olive-backed oriole calling in a 20-year old plantation that includes manna gums, blue gums and a shrubby understorey.

The oriole is not a common bird, so this sighting was a very satisfying one for the landowner who did the planting 20 years ago.