Geometrid Moth
Cleora (?)
At lights, Kirinyaga south of Mt Kenya, 31 May 2017.
The characteristic locomotion of the immature stage, a larva (caterpillar), gives a common name for this group of moths. The wings of geometrids tend to be thin and fragile and generally held flat against the substrate when alighted; the adults are short-lived and don't feed as adults. Many geometrids also have exquisite camouflage patterns that make them virtually invisible when perched on natural substrates. Birds and other insect predators have learned that lots of easy prey can be had around lights.