Naturalists across the state are commenting that the handsome gum emperor moth is not seen as frequently as it once was. There has been concern expressed about its future.
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Older people remember seeing the large pinkish-brown moths and the large fleshy green caterpillars. Younger generations don’t know them at all. The emperor gum moth is indeed an impressive insect. With a wingspan of 12 – 15 centimetres, it is usually soft brown, with prominent “eye-spots”.
The caterpillars are large, bright green and fleshy. They can reach finger-size when mature. Small spiky protuberances on the back are eye-catching, and a yellow stripe along the side is another feature.
Both the caterpillars and the moths are scarcer now than they once were. One reason could be habitat loss, especially the loss of eucalypts in suburbia where the moths and caterpillars are more readily seen.
The European wasp has also been blamed, but these insects themselves are not as common as they were 15 or 20 years ago.
Will a year or two of “normal” rainfall see more emperor gum moths appear? Probably not, because the apparent decline started before the dry years commenced in 1996.
There is no clear cause of the decline.
Fortunately there are still caterpillars and moths to be seen from time to time, and the firm furry cocoons, 25-30 millimetres long, are still found in local forests.
Adult emperor gum moths do not feed. They survive for just a couple of weeks, usually dying soon after mating.
Although eucalyptus leaves are the caterpillars’ main food, peppercorn leaves are also eaten, as well as those of liquid amber and silver birch.
A local naturalist has reported being unable to locate any caterpillars on peppercorn trees - a different situation from a decade or two ago.
Yellow bladderwort
A reader has sent a photo of an uncommon plant known as yellow bladderwort.
The odd-sounding name belies this rootless aquatic plant’s delicate nature, and the beauty of its small yellow flowers. There are not many local records of yellow bladderwort. The recent photo was taken in a well-vegetated dam at Napoleons. There are other records of yellow bladderwort from Lake Wendouree.
The plant has fine leaves somewhat like those of lake water-milfoil – the “lakeweed” of Lake Wendouree. Its yellow flowers appear above water in summer and early autumn.
The name bladderwort comes from tiny plankton-catching “bladders” on the leaves.
