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Peppered Moth

Biston betularia

Peppered Moth , Darwin's Moth

A close up photograph of a peppered moth against a tree bark Biston betularia

Biston betularia(js)02 Lodz(Poland)

by Jerzy Strzelecki. CC BY 3.0

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The peppered moth is a typical textbook example in evolutionary biology. These moths are a variable moth, and the irregularity of the wing patterns are specially adapted to mimic a lichen-covered tree. There is another, rarer morph that's black-bodied and black-winged. It's often referred to as Darwin's moth because its history provides a perfect example of how new species could evolve by chance. In Britain, during the 1800s, it was first noted that a black morph (the melanic form) was becoming more prominent in areas experiencing high rates of pollution. The soot in the air was killing lichen and staining tree bark black. These moths started to thrive in such conditions because they were able to retain camouflage on a soot-stained tree. These went on to become the strongest surviving morph in polluted areas. This is an excellent example of natural selection, a theory postulated by Darwin. The theory proposed that if only the fittest individuals survived, this would facilitate the emergence of new species through successive adaptation or chance mutations. Of course, evolution is a slow process, but the example demonstrates natural selection in action. It also shows that when presented with sudden environmental changes, some species can adapt quickly by chance, whereas others won't do so well.
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Traits

Caterpillar food plants include bramble, rose, hawthorn, elm and willow.
These moths make an excellent snack for garden wildlife like hedgehogs, bats and birds.

Appearance

Adults: Mature moths are masters of disguise. They can be variable, but most morphs today are a mixture of speckled white, grey, black and browns. The body is fluffy and fairly wide. They're a medium-sized moth, with the females reaching roughly 5.5cm with males amounting to about half of this. The black morph is identical but completely black in appearance. Larvae: The larvae are also highly variable. They've adapted to perfectly mimic a twig or branch so they can be difficult to spot at first. They turn the colour of the foodplant they've fed on as an immature, so they can be various browns and greens. This is done through similar mechanisms used by animals such as cuttlefish and chameleons. This serves to prevent detection by predators. Pupae: The cocoons overwinter below ground. They are stout, red-brown and shiny. Eggs: Tiny (1mm) laid in large clusters that are pearly white-green beneath the food plant.

Symptoms

Caterpillars may be found feeding on bramble, rose, hawthorn, elm and willow. Moths perch on tree bark during the day.

Activity

Nocturnal

Personality

Order

Lepidoptera

Family

Geometridae

Metamorphosis

Complete

Distribution

Europe, Asia and North America.

Biological treatment

These caterpillars are harmless in most cases. They're solitary feeders seldom causing severe defoliation in trees.

Chemical treatment

It's not advised to remove these insects from the environment because of the small risk they pose to garden plants.

Attracts

The caterpillar can use a whole range of trees as the primary food plant!
A Prunus spinosa plant with green leaves and black purple berry fruits

Blackthorn

Prunus spinosa

Hawthorn

Crataegus monogyna

A Downy Birch Betula pubescens plant with green leaves on a tree branch

Downy Birch

Betula pubescens

Common broom

Cytisus scoparius

Blackcurrant

Ribes nigrum

Hop

Humulus lupulus

Common Silver Birch

Betula pendula

Goat Willow

Salix caprea

Fagus sylvatica f. purpurea

Fagus sylvatica f. purpurea

A close up of a green Castanea sativa plant

Sweet Chestnut

Castanea sativa

Repels

Birds and bats predate these moths and caterpillars.
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