Goliath Stick Insect

The goliath stick insect is among the heaviest and longest phasmid species found in Australia, with females reaching an overall length approaching a quarter of a metre when the legs are included. Its body is typically bright leaf-green with pale yellow stripes running along the sides, allowing it to blend almost seamlessly into the eucalyptus canopy it inhabits.

Native to the coastal regions of eastern and northern Australia and parts of New Guinea, this species spends most of its life high in tree foliage, feeding on eucalyptus and related leaves. Though its bulk and length are impressive, it is a harmless plant-feeder that relies on camouflage as its main defense, only revealing bright hindwing coloration as a last-resort startle display.

• Large, elongated body, typically bright green with cream or yellow lateral stripes
• Females are considerably larger and heavier-bodied than the more slender males
• Males possess fully developed wings capable of weak flight; females have shorter wings and rarely fly
• Hindwings flash red or pink markings when opened in a defensive display
• Long, thin legs and antennae that reinforce the leaf-and-twig disguise
• Distinguished from smaller Australian phasmids by its sheer size and vivid coloring

This species occurs along the eastern coast of Australia, from Queensland down into New South Wales, as well as in parts of New Guinea, favoring subtropical and tropical eucalypt forest and woodland. It lives primarily in the tree canopy, descending occasionally, and is most commonly observed at night when active on foliage, with sightings peaking during the warmer months.

Goliath stick insects are nocturnal herbivores that feed on the leaves of eucalyptus and related trees, remaining still and camouflaged among branches by day. When threatened, an individual may rock back and forth to mimic wind-blown foliage, or suddenly flare its wings to expose bright hindwing patches and startle a predator before dropping away or gliding off. Males, being lighter and fully winged, are more mobile and can make short flights between trees, while the heavier females tend to stay closer to a single feeding area. As foliage feeders, they contribute modestly to canopy leaf turnover and serve as prey for birds and other predators.

Females drop numerous hard-shelled eggs to the forest floor over an extended period, and these eggs may take several months to over a year to hatch depending on conditions. Newly hatched nymphs are dark-colored and more slender, gradually developing the green coloration and elongated form of adults through a series of molts. There is no pupal stage, as phasmids undergo incomplete metamorphosis. Development to full adult size can take many months, with sexual maturity reached after the final molt.