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The Geometridae, from Latin geometres that means surveyors, (Geometridae, Leach, 1815) are a family of Lepidoptera (butterflies), which includes about 21,000 species.
Most have cryptic drawing and coloring, suitable for camouflage in the environment, but some, such as those of the genus Abraxas, have vibrant aposematic colors, to warn predators to have an unpleasant taste. The caterpillars of some Geometridae are very mimetic and defend themselves from their enemies birds taking the shape, the color and the immobility of a twig.
The main distinguishing feature of this family is the unique structure of the caterpillar that has two pairs of pseudo-paws (false paws) at the rear end of the body, more precisely in the sixth and ninth + tenth abdominal segment, and it does not have it in the middle; this fact forces him to walk by moving forward alternately first the front and then the rear of the body strongly hunching the back. Because it seems that these caterpillars are measuring the ground, it has been given them the name of “surveyors” and that of the Geometridae to the family that includes all the species that have this feature.
