Not only are its wings a stunning uniform iridescent blue-green, but the head and body are similarly coloured as well.

Even the black antennae and legs have a trace of iridescence.

The wingspan of this small moth is between 20 and 30 millimetres and the iridescent colour varies a little, with most variation the result of the way it is viewed.

Glossy blue-green is the usual colour, but blue may dominate at certain angles, and sometimes the blue tone is almost absent, resulting in a glossy light green moth.

On dull days, the moth may appear to have a grey shade over its bright satiny blue-green.

The two hindwings are dull grey-brown. The gloss of the front wings rubs off readily when handled.

With wings about 12mm long, males are a couple of millimetres larger than females, which have a stouter body with an orange tip, but there is no difference in wing colour.

The satin-green forester moth is seen mostly on sunny spring days, sometimes extending into summer as well. It is not active at night.

It is a fast-flying moth, often difficult to photograph, and often flying quickly away when approached.

Is the satin-green forester moth specially attracted to yellow flowers?

Sometimes this seems to be the case, but more research is needed. It visits white (grass-tree, blackberry, rice-flower) and other coloured flowers as well, but it may be more readily attracted to yellow, such as the everlasting flower pictured.

Perhaps yellow flowers dominate at its main flying time. The yellow-flowered guinea-flower plant is one of the caterpillars' favourite food plants.

There are many species of forester moths, many of which are not brightly-coloured.

MUSK DUCK DUCKING

A male musk duck made several dives at times of 35 to 40 seconds. This seemed a long time for a bird to be underwater. The extended times may have been prompted by his apparent failure to find food on any of the dives observed.

Twenty to 30 seconds is considered an average diving time for a musk duck.

Perhaps the larger males dive slightly longer than the smaller females. A dive of 40 seconds would be near the maximum range.

At one stage, the diving musk duck came close to a dusky moorhen, which honked its disapproval, presumably due to youngsters hidden in reedbeds.

Male musk ducks are known to eat small ducklings, and chicks of other waterbirds, so the moorhen had reason to be concerned.

What is this tree at Brown Hill Park, close to Humffray Street? It is a most unusual shape. J.G., Newington

This is a river she-oak, a native of NSW and Queensland.

It is certainly a very unusual and interesting shape. A river she-oak is normally an upright tree with one main trunk.

This tree was probably damaged when young, with a few side branches taking the place of the broken trunk.

After a while another slender trunk has grown from the base, providing the unusual shape we see today.

There are three normal-shaped river she-oaks near your specimen.

River she-oaks are either male or female, with the females being those with cones.

The river she-oak grows naturally along rivers and creeks.

Its botanical name is Casuarina cunninghamiana.

Our local she-oaks have the scientific name of Allocasuarina, but the river she-oak has retained its long-term name of Casuarina.