The wings are orange-yellow with a varying degree of speckling. The outer of the two cross-lines on the forewing sweeps in a gentle arc ending at least three quarters of the way along the leading edge. This species could be confused with other similar thorn species – the Dusky Thorn, August Thorn and September Thorn.
The larvae can be seen from early May to July. Overwinter as eggs on the foodplant.
Size and Family
- Family – Thorns, beauties, umbers and allies (Geometridae)
- Medium Sized
- Wingspan Range – 32-40mm
- UK BAP: Not listed
Caterpillar Food Plants
Downy Birch (Betula pubescens) and Silver Birch (Betula pendula), Alder (Alnus glutinosa), limes and elms.
Woodland, scrub, parks and rural gardens.
- Countries – England, Wales, Scotland and Ireland
- Generally well distributed and frequent throughout England, Wales, mainland Scotland, Ireland and the Channel Islands. Fairly widespread but not frequent on the Isle of Man.