Status Widespread but local, only recorded in small numbers each year, although increasingly in recent years.
The caterpillars, which are seen from July to September, are up to 65mm long, bright green with purple and white markings. When threatened they can rear up, revealing a red and black 'face' before shooting out formic acid!
The orangey-brown eggs are laid on the upper surface of Willow or Poplar leaves, typically in small groups of two or three, hatching into caterpillars within around 14 days.Recorded in 65 (88%) of 74 10k Squares. First Recorded in 1834. Last Recorded in 2025. Additional Stats |