The geometer moths are moths belonging to the family Geometridae of the insect order Lepidoptera, the moths and butterflies. Their scientific name derives from the Ancient Greek geo γεω, and metron μέτρον "measure" in reference to the way their larvae, or inchworms, appear to measure the earth as they move along in a looping fashion. Geometridae is a very large family, containing around 23,000 described species; over 1400 species from six subfamilies are indigenous to North America alone. A well-known member is the peppered moth, Biston betularia, which has been the subject of numerous studies in population genetics. Several other geometer moths are notorious pests.

Lepidoptera or lepidopterans is an order of winged insects that includes butterflies and moths. About 180,000 species of the Lepidoptera have been described, representing 10% of the total described species of living organisms, making it the second largest insect order with 126 families and 46 superfamilies. and one of the most widespread and widely recognizable insect orders in the world.