A moth is an insect closely related to the butterfly. Both are of the order Lepidoptera. People who study or collect these insects are called lepidopterists. Moths are generally considered nocturnal, but there are crepuscular and day-flying species. They can be distinguished from butterflies in several ways.
Moths as pests
Moths are commonly regarded as pests because the larvae of a few species eat fabric such as clothes and blankets. These can be repelled by the scent of cedar or naphthalene (the chemical used in mothballs).
Others may have caterpillars which are agricultural pests, such as the Codling Moth.
Attraction to light
Moths are notable for apparently being attracted to light, or more specifically, are known to circle ambient objects. The reason for this behaviour is not known. Moths do not fly directly away from the light due to a visual distortion called a Mach band. One researcher, Henry Hsiao, has conjectured that moths, as nocturnal creatures, fly towards the darkest part of the sky in pursuit of safety. Moths are thus inclined to circle ambient objects in the Mach band region, usually at a radius of about one foot, depending on the species.
Night blooming flowers usually depend on moths (or bats) for pollination, and artificial lighting can draw moths away from the flowers, impacting the plant's ability to reproduce. Light pollution is coming under increasing scrutiny as a source of many subtle ecological changes.