The Emperor’s New Clothes
The Emperor Gum Moth (Austrocaligula eucalypti) – previously Opodiphthera eucalypti, pictured below is one of our largest summer moths. Like all butterflies and moths its lifecycle consists of four major steps – egg, larva (known as a caterpillar), pupa and adult. This is known as complete metamorphosis (i.e. incorporates all four steps). Some insects undergo fewer steps in their lifecycle e.g. grasshoppers and cockroaches. This is termed incomplete metamorphosis.
During the larval stage, caterpillars grow and then have to moult as they become too large for their skins. Emperor Gum Moth caterpillars go through five such stages. In many caterpillars, each stage or instar looks like the previous one only bigger. However the Emperor Gum Moth caterpillar changes its livery with every moult.
The first instars are almost entirely black, pictured above right. With successive moults the caterpillars become more colourful and develop the characteristic tubercules and spikes. Last week I discovered young gums trees festooned with 3rd stage instars, pictured above left. During the fifth (last) stage the caterpillar takes on the familiar lime-green colour with a yellow stripe (pictured left).
The Emperor does indeed have new clothes.
Focus On Fauna 