墨脱健䗛 (Sosibia medogensis)

A walking twig that calls Medog home

In the rainforests of Medog you learn to look twice at every twig. On 7 August 2024, one of those twigs turned out to be a stick insect, and it was kind enough to hold still for the camera while I worked out what I was looking at. The longer I stared, the more the shape resolved itself: long body, longer legs, antennae held like feelers testing the air.

This is Sosibia medogensis, a stick insect of the family Lonchodidae (order Phasmida). The name gives away its home: medogensis simply means from Medog. Sosibia species are slender and twig-like, with long legs and long antennae, and they spend their days motionless among the vegetation, trusting shape and stillness rather than speed.

Stick insects are leaf-eaters and mostly nocturnal, coming out to feed under cover of darkness. Their camouflage is so complete that the main threat to many of them is being overlooked entirely, which suits them just fine. Predators walk past them a hundred times a day; the ones that notice them usually do so by accident. And if a predator does grab one, many stick insects can shed a leg and grow it back at the next moult, leaving the attacker holding nothing but a leg-shaped snack.

Some stick insects sway gently as they walk, mimicking a twig moving in the breeze, a trick that fools birds and occasionally entomologists. A species named after a single valley is a reminder that Medog’s insect life is still being mapped, one walking twig at a time.