This curious looking caterpillar was found inside Kadri Park in Mangalore when I went for a stroll on Sunday afternoon. Light was terribly bright and I had no flash with me nor any method to shade. This moth caterpillar belongs to family Geometridae. Most probably caterpillar of Dysphania militaris moth. It is called Inch Worm because of its peculiar locomotion pattern. It was acting as though it is bud on top of that twig which it had finished eating. the shrub was full of these caterpillars.
Many Geometrids moths have slender abdomens and broad wings which are usually held flat with the hind wings visible. As such they appear rather butterfly-like but in most respects they are typical moths: the majority fly at night, they possess a frenulum to link the wings and the antennae of the males are often feathered. They tend to blend in to the background, often with intricate, wavy patterns on their wings.
The name Geometer (earth-measurer) refers to the means of locomotion of the larvae or caterpillars, which lack most of the prolegs of other Lepidopteran caterpillars. Equipped with appendages at both ends of the body, a caterpillar will clasp with its front legs and draw up the hind end, then clasp with the hind end (prolegs) and reach out for a new front attachment – creating the impression that it is measuring its journey. The caterpillars are accordingly called loopers, spanworms, or inchworms. They tend to be green, grey, or brownish and hide from predators by fading into the background or resembling twigs. Some have humps or filaments (see Filament-bearer image). They are seldom hairy or gregarious. Typically they eat leaves. However, some eat lichen, flowers or pollen. Some, such as the Eupithecia, are even carnivorous.