The New Guinea Spiny Stick Insect, or more specifically Eurycantha calcarata, is a large species of ground dwelling stick insect from New Guinea. The Phasmid Study Group give it the species number psg 23. Sometimes it is called Giant Spiny Stick Insect, but this is too confusing as there is also a different species called Giant Prickly Stick Insect.

This species of stick insect is very bulky and big. It looks more like a big branch than a twig or stick. Its adult color is always dark brown, sometimes even close to black and they appear quite glossy. The nymphs can vary in color a lot. They are usually a mix of different shades of green and brown in a moss-like pattern. The legs of this stick insect are thick and prickly. Adult males have a long thorn on their hind legs, while the females do not have this. Adult females have an ovipositor at the end of their abdomen which kind of looks like a stinger but it is not used in defense.
Female reach a length of 11 to 15 cm while the males reach around 11 cm.