Peppered Moth

The peppered moth is a member of the family Geometridae, the geometer or 'inchworm' moths, named for the looping crawl of their larvae. It is native to temperate regions of Europe, Asia, and North America and is one of the most scientifically famous moths in the world due to its role in studies of natural selection.

The species typically shows a pale, salt-and-pepper speckled wing pattern that provides camouflage against lichen-covered tree bark. During the industrial era, a dark (melanic) form became common in polluted, soot-darkened areas where the pale form was more visible to predators, a phenomenon studied extensively as a case of rapid evolutionary change linked to environmental conditions.

Beyond its historical significance, the peppered moth is ecologically unremarkable but representative of its family: a nocturnal, bark-resting moth whose larvae feed on a wide variety of deciduous trees and shrubs.

• Wings finely speckled with black and white scales in a mottled 'peppered' pattern, giving excellent camouflage against lichen-covered bark.
• A darker melanic form exists with almost entirely blackish-brown wings, historically more common in industrially polluted areas.
• Stout, moth-typical body held flat against bark at rest, wings spread out to the sides rather than tented.
• Wingspan of roughly 1.5 to 2.4 inches; caterpillars are twig-like inchworms (loopers) that move by arching the body, camouflaged to resemble a small brown or green twig.

Found throughout much of Europe, temperate Asia, and North America, in woodlands, hedgerows, parks, and gardens with deciduous trees. Adults are nocturnal and rest by day on tree trunks and branches where their mottled pattern blends with bark and lichen; the main flight period runs through late spring and summer.

Adults are active at night, when they fly in search of mates, and spend daylight hours motionless on bark, relying on camouflage rather than flight to avoid predators such as birds. Larvae are generalist feeders on the foliage of many deciduous trees and shrubs including birch, oak, and willow, moving with the characteristic looping gait of geometrid 'inchworm' caterpillars and often holding a stiff, twig-like pose when at rest to avoid detection.

Eggs are laid on host plant leaves and hatch into looper caterpillars that feed and molt through several instars while mimicking twigs for camouflage. Mature larvae drop to the ground to pupate in the soil or leaf litter. The species overwinters as a pupa, with adults emerging in late spring to summer; there is generally one generation per year in cooler climates.