Macleay's Spectre

Extatosoma tiaratum — Macleay's spectre (also called the giant prickly stick insect or Australian spiny leaf insect) — is one of the most extraordinary stick insects in the world and one of the most popular giant pet stick insects worldwide. The species is native to northeastern Australia (Queensland and northern New South Wales) where it occurs in eucalyptus and acacia forests. Adults are 15-20 cm body length (much larger than most stick insects), with the species' diagnostic features: HEAVILY ARMORED BODY with elaborate SPINY LEAF-LIKE PROJECTIONS along the body and legs (looking like a piece of dead vegetation with the moss and lichen still attached), DRAMATIC SEXUAL DIMORPHISM (FEMALES are larger and heavier with reduced wings — essentially flightless; MALES are smaller, slimmer, with FUNCTIONAL WINGS — capable of flight), and color polymorphism (green, brown, or mottled forms in the same population, depending on substrate during development). The species' DEFENSIVE REPERTOIRE is one of the most extensive in any stick insect — Macleay's spectre has FOUR DIFFERENT DEFENSIVE BEHAVIORS: (1) LEAF MIMICRY AT REST — the elaborate spiny leaf-like body morphology provides exceptional camouflage when the insect is motionless on host plant vegetation, with the spines and projections breaking up the body silhouette and matching dead leaf or lichen-covered branch backgrounds; (2) SCORPION-MIMIC THREAT POSTURE — when threatened, the insect CURLS THE ABDOMEN FORWARD OVER THE BACK in a posture closely resembling a SCORPION'S RAISED STING. The scorpion-mimic posture is one of the most-cited examples of unrelated arthropod mimicry — Macleay's spectre is in order Phasmatodea (stick insects, no relation to scorpions in class Arachnida) but has evolved a defensive display that closely mimics scorpion threat behavior. Predators that have learned to avoid scorpions are deterred by the unrelated stick insect display; (3) FLIGHT — winged adult males can fly to escape from predators (females are flightless and rely on the other defensive behaviors); (4) CHEMICAL DEFENSE SPRAYING — adults can spray a TOFFEE-SCENTED MILKY DEFENSIVE SECRETION at threats from glands at the prothorax (similar to but milder than the dramatic chemical sprays of two-striped walking sticks Anisomorpha buprestoides — see Wild Files). The species is one of the most popular giant pet stick insects worldwide — kept by insect enthusiasts globally because of the dramatic size, intricate body morphology, easy captive husbandry (feeds on eucalyptus, oak, brambles, raspberry, rose), and dramatic defensive displays. The species is the foundational case study in modern textbook discussions of giant stick insect biology and Australian arthropod conservation. Females are PARTHENOGENETIC capable — though males are common in wild populations and most captive populations include males, females can produce viable offspring without mating. The species is harmless to humans (no venom, no biting strength, the chemical spray is harmless to humans).