The green form of the Macleay’s Spectre (Extatosoma tiaratum) is a naturally occurring colour expression that becomes most striking as the insect approaches adulthood. While early‑stage nymphs often begin life in the familiar brown twig‑like pattern, individuals destined to become “lichen morphs” gradually shift through mottled greys, olives and pale greens as they grow. This transformation is slow and subtle, usually becoming obvious from mid‑instar onwards, when patches of green begin to appear along the legs, abdomen and thorax. These areas expand with each moult, giving the insect a progressively more lichen‑covered appearance.
 
As they reach their final instar and prepare for adulthood, the colour change accelerates. The cuticle develops a complex mix of greens, creams and muted browns, mimicking the texture of lichen encrusted bark. By the time the adult emerges, the green morph is fully expressed: a soft, leafy green base overlaid with irregular pale blotches and delicate patterning that breaks up the insect’s outline. This camouflage is structural rather than pigment‑driven, meaning the tones are produced by the micro‑texture of the cuticle and can vary with light, humidity and individual genetics.
 
Adult females, with their broad bodies and slow movements, display the green morph most vividly. Males, being slimmer and more mobile, often show a lighter, more muted version of the pattern. In both sexes, the green coloration is an adaptive form of crypsis, allowing the insect to resemble lichen‑covered twigs rather than fresh leaves. This makes the green morph particularly effective in the wild and especially attractive in captivity, where its soft, mossy tones stand out among phasmids.