Common Heath Ematurga atomaria

The family name "geometer" — meaning earth-measurer — refers to the caterpillars, which move by looping their body in a distinctive arching motion, appearing to measure the ground as they inch forward. These "inchworms" or "loopers" lack legs in the middle section of the body, forcing this unmistakable gait. Unlike most moths, this species is a dayflier, commonly seen fluttering low over heathland and grassland in full sunshine — behavior more typical of a butterfly.

Males and females look quite different from each other: males are a warm, speckled buff-brown, while females tend to be paler and more heavily marked. Spot one basking on a heather stem on a warm spring morning and you're looking at one of the heathland's most characteristic invertebrates.