Geometer moths

Definition

A very large family (Geometridae) of moths in the order Lepidoptera, comprising roughly 23,000 described species worldwide. The family name derives from Greek γεω- (earth) and μέτρον (measure), referring to the characteristic looping locomotion of their larvae—commonly called inchworms or loopers—which appear to "measure the earth" as they arch their bodies forward. Adults typically have slender bodies and broad wings, often cryptically colored as bark or leaf mimics. The family includes economically significant pests and classic evolutionary study organisms.

Etymology

From Greek γεωμέτρης (geōmétrēs, "land-measurer"), via the larval locomotion of inchworms.

Example

The peppered moth (Biston betularia), a European geometrid, became famous for demonstrating industrial melanism through documented shifts in wing coloration from light to dark morphs correlated with soot-darkened tree trunks during the Industrial Revolution.

Synonyms

• Geometridae
• geometrid moths
• inchworm moths

Related Terms

• Lepidoptera
• inchworm
• industrial melanism
• Biston betularia
• Ennominae
• Larentiinae
• cryptic coloration
• looping locomotion

Usage Notes

Geometridae is among the most species-rich lepidopteran families. The larvae are immediately recognizable by having only two or three pairs of prolegs at the posterior end, forcing the looping gait. "Geometer moth" and "geometrid" are used interchangeably; "inchworm moth" is more colloquial. Several subfamilies (Ennominae, Larentiinae, Sterrhinae) are commonly encountered in field guides. Many species are nocturnal and attracted to light traps.