Twig Mimic Geometrid Caterpillar

This caterpillar did an excellent job of trying to convince me that it was a stick. When I disturbed it, it stood erect on its prolegs and was completely motionless; thus perfecting its mimicry of a twig. It was gray with some pale pinkish markings and was approximately 3cm long.

Larvae generally have two pairs of prolegs at the posterior end, rather than the usual five pairs that most lepidopteran caterpillars have. The lack of prolegs in the middle of their body compels them to employ their peculiar method of locomotion: drawing the posterior end up to the thoracic legs to form a loop, and then extending the body forward. Geometridae means "earth-measurer" in Greek, which describes their "inching" movements.