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A yellow-tail moth resting on a brick wall, its abdomen curled up to reveal the distinctive yellow tail

Yellow-tail © Tom Hibbert

A yellow-tail moth resting on a brick wall

Yellow-tail © Tom Hibbert

Yellow-tail moth caterpillar

Yellow-tail moth caterpillar ©Chris Lawrence

The caterpillar of a yellow-tail moth, feeding on leaves

Yellow-tail caterpillar © Tom Hibbert

Yellow-tail

Enw gwyddonol: Euproctis similis
This snowy white moth is easily mistaken for the similar brown-tail, until it lifts its abdomen to reveal a burst of golden-yellow.

Species information

Ystadegau

Forewing length: 16-23 mm

Statws cadwraethol

Common

Pryd i'w gweld

Adult: July-August
Caterpillar: September-June

Ynghylch

The yellow-tail is found in a broad range of habitats across the UK, from woodlands and hedgerows to urban parks and gardens. The moths fly in July and August, though there can be a small second generation in October. They can sometimes be found resting amongst the leaves of their foodplants during the day, but are more often seen as they're attracted to lights at night.

The caterpillars appear in September, feeding on a wide selection of broadleaf trees and shrubs, including hawthorns, blackthorn, oaks, roses, hazel, and willows. They'll occasionally eat grasses and other herbaceous plants, too. They spend the winter as a small caterpillar, within a protective silk tent tucked away somewhere on or under the foodplant. Unlike brown-tail caterpillars, which share their silk tents, each yellow-tail gets a shelter to itself.

The caterpillars emerge again in April to carry on feeding, when they can be quite obvious resting on top of leaves. When they're fully grown and ready to become adult moths, they pupate in a hairy silken cocoon, either hidden amongst foliage or in the leaf litter below.

Sut i'w hadnabod

Moths are mostly snowy white, though males usually have some dark smudges near the trailing corner of the forewing (faint or absent in females). They have a white body with a golden-yellow or orange-brown tip to the abdomen. This yellow 'tail' is usually hidden by the wings at rest, but they will sometimes lift their abdomen up so the yellow end sticks out above the wings.

Caterpillars are black, with a slight hump not far behind their head. They bristle with tufts of long black hairs and shorter white ones. Two bright red or orange lines run close together along their back, sometimes broken into dashes, with a row of white markings either side of them. They also have a thick red line along each side of their body.

Dosbarthiad

Common and widespread in England and Wales, more localised in southern Scotland and eastern Northern Ireland. Widespread on the Isle of Man and the Channel Islands.

Habitats

Roeddech chi yn gwybod?

Yellow-tail caterpillars have even been found feeding on Japanese knotweed, a plant that was introduced to the UK from east Asia and causes lots of problems for the wildlife here.