Adult male
Flies at night in winter. Wingspan 22-28 mm, forewings rounded, greyish brown and with darker wavy cross-lines.
Adult female
Found on tree trunks and branches in winter. Wings reduced to stubs; body 5‑6 mm long, dark brown mottled with greyish yellow.
Egg
Occur singly in bark crevices; 0.5 x 0.4 mm; oval, pale yellowish-green, soon becoming orange red with pitted surface.
Larva
Looper habit, up to 25 mm long. Pale green with dark green dorsal stripe and several whitish or creamish-yellow stripes along back and sides, including a pale yellow line passing through the spiracles. Abdomen has two pairs of prolegs.
Other pests with which winter moth may be confused
Tortrix moth caterpillars
- Tortrix moth caterpillars often occur in blossom trusses in spring and, when tiny, can be confused with winter moth caterpillars.
- However, tortrix moth caterpillars have 5 pairs of abdominal prolegs.
Clouded drab moth caterpillars
- Clouded drab moth caterpillars occur commonly in the shoots of apple post blossom and have a similar green colour appearance to winter moth but are quite different if examined closely.
- They gave 5 pairs of abdominal prolegs.