Wingspan of 36-42 mm. Forewings bluish-grey to black or lighter purple grey with darker mottling, a silver-white stigma with long lateral part and a patch of chestnut brown near the outer edge of the stigma.
Up to 25 mm long, smooth with only two pairs of abdominal prolegs. Abdomen green with a thin white lateral line. Head green.
Round white to cream coloured, laid singly on the under surface of leaves.
Throughout Europe, parts of Asia and has now been introduced to Northern America.
A range of crops including peas, sugarbeet, alfalfa, beans and spinach.
Larvae feed on leaves producing ragged edged holes in the leaf and on the leaf margins. The major damage is caused by later instars attacking the inner heads of crops.