Moth


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Moths
Emperor Gum Moth
Emperor Gum Moth
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Lepidoptera

A moth is an insect closely related to the butterfly. Both are of the order Lepidoptera. The division of Lepidopterans into moths and butterflies is a popular taxonomy, not a scientific one. Sometimes the names " Rhopalocera" (butterflies) and " Heterocera" (moths) are used to formalise the popular distinction.

Most species of moths are nocturnal, but there are crepuscular and diurnal species. They can be distinguished from butterflies in several ways.

People who study butterflies and/or moths are called lepidopterists; the study of butterflies is known as butterflying, and the study of moths mothing, the latter giving rise to the term mother for someone who takes part in this activity – sometimes written with a hyphen inserted (moth-er) or as moffer to distinguish it from the word for a female parent (in spoken English, confusion does not arise as the two are pronounced differently).

Economic significance of moths

A moth caterpillar eating a leaf
A moth caterpillar eating a leaf

Moths, and more particularly their caterpillars, are a major agricultural pest in many parts of the world. The caterpillar of the Gypsy moth causes severe damage to forests in North East USA, where it is an exotic species. The Codling moth also does extensive damage, especially to fruit farms.

Other moths are commonly regarded as pests because their larvae eat fabric such as clothes and blankets made from natural proteinaceous fibers such as wool or silk. They are less likely to eat mixed materials containing artificial fibres. There are some reports that they can be repelled by the scent of wood from juniper and cedar, by lavender or by other natural oils. However, many consider this unlikely to prevent infestation. Naphthalene (the chemical used in mothballs) is considered more effective, but there are concerns over its effects on health. Moth larvae are not killed by freezing the items which they infest.

Moths are sturdy and usually are more resistant to pesticides than mosquitos and flies.

Other moths are farmed. Especially the Silkworm (the larva of a moth) is farmed for the silk with which it builds its cocoon. The silk industry produces over 130 million kg of raw silk, worth about 250 million US dollars worldwide.

Attraction to light

A moth attracted by porchlight
A moth attracted by porchlight

Moths are apparently attracted to light, or more specifically, are known to circle bright objects. The reason for this behaviour is not known. It may be moths navigate by maintaining a constant angular relationship to a bright celestial light (such as the moon), but on encountering a bright artificial light it navigates by maintaining a constant angle to the light, resulting in the moth flying in a spiral until it hits the light source.

However, researchers such as Henry Hsiao suggest the reason for moths circling lights has to do with a visual distortion called a Mach band. Henry Hsiao conjectures 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, affecting the plant's ability to reproduce. Light pollution is coming under increasing scrutiny as a source of many subtle ecological changes.

Moth species

Large and dramatic Moth species include:

  • Death's-head Hawkmoth Acherontia sp.
  • Luna Moth Actias luna
  • Atlas moth Attacus atlas The largest moth in the world
  • Emperor Gum Moth Opodiphthera eucalypti
  • Polyphemus Moth Antheraea polyphemus


Moths that are of economic significance include:

  • Gypsy moth Lymantria dispar
  • Cotton bollworm or corn earworm Helicoverpa zea, a major agricultural pest
  • Codling moth Cydia pomonella, a pest mostly of apple, pear and walnut trees
  • Light brown apple moth Epiphyas postvittana
  • The silkworm Bombyx mori is the larva of a moth.

Other notable moths:

  • Peppered moth Biston betularia The subject of a now well known study in evolution.

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