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The name "Geometridae"
ultimately derives from geometer
("earth-measurer"). This 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 rely on their superb
camouflage to hide from predators.
Many Geometrids have slender
abdomens and broad wings which are usually held
flat with the hindwings 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. In some species, females have
reduced wings (e.g. winter moth and fall
cankerworm). |