Giant Prickly Stick Insect

Female adult E. tiaratum are covered with thorn-like spikes for defense and camouflage. Their long, rounded bodies grow to about 8 inches (20 cm) long. The females are further described as "heavy-bodied, brachypterous and (having) numerous spines and integumental expansions on the body and legs, including a tuft of spines on the conical occiput of the hypognathous head". The wings of the female are too small for flying, especially when she is gravid.

Exhibiting the sexual dimorphism of many similar insects (particularly other phasmids as well as mantises), males are small and thinner, growing only about 11 cm in length and have three ocelli. Males lack the thorny growths except for spikes around their heads. They have long wings and are good flyers who readily take to the air if disturbed or in search of females.

Both genders, when threatened, stand on the front and middle legs, pointing their abdomen up or to the side in a sort of "scorpion" pose. They fold back their legs to defend themselves if anything comes in contact with their abdomen. Adult males can release a defensive odor that humans might not find offensive as it "is rather reminiscent of peanut butter or toffee".

E. tiaratum also take a curved pose when it hangs inverted amongst foliage with "its highly procryptic abdomen curled over its back." Like many stick insects, E. tiaratum sway back and forth or side to side when disturbed. They also move this way to blend with foliage rustling in the wind. Individual E. tiaratum vary in color and appear brown, mottled brown, dun, green, a reddish color, a cream color, a yellowish color, and even entirely white.
E. tiaratum are vegetarians and breeders recommend feeding them bayberry, bramble, eucalyptus (their natural food in their native Australia), hawthorn, oak, photinia, raspberry, rose, and salmon berry (red or yellowOne source reports good results from using feeding these insects California Wax Myrtle (Myrica californica) as the sole food plant.