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Guides
Geometridae
geometer moths, geometrid moths, inchworms, spanworms, loopers, cankerworms, measuring worms
Geometridae is one of the largest families of moths, with approximately 23,000 described species worldwide. The family name derives from Greek "geo" (earth) and "metron" (measure), referring to the distinctive looping locomotion of their larvae, commonly called inchworms or loopers. These caterpillars possess only two or three pairs of prolegs at the posterior end, compared to five or more pairs in most other Lepidoptera, forcing them to arch their bodies in a characteristic "measuring" gait. Adults are typically nocturnal with slender bodies and broad wings, often exhibiting cryptic coloration that provides camouflage against bark and vegetation.