Description

Adult

Forewing length of 16-20 mm. Forewings olive-grey with pale greenish and white markings. One of these markings is a silvery white kidney shaped spot and the medial line is grey. Hindwings are pale grey with a slight yellowish sheen and a dark grey marginal band. The head is dark grey brown and the anterior thorax bears a weak dark tuft.

Larvae

Newly hatched larvae are ca. 3 mm long, pale green with a pale yellowish stripe along each side. Final instars reach 40 mm long and are variable in colour with green, brown or velvety black forms. A yellowish orange stripe is present along each side and the head is pale brown. The black form has 3 broken white lines along its back.

Eggs

Sculptured and ribbed, initially white and becoming darker with age. Laid in clusters of 50-500 eggs on the lower surface of leaves. Eggs hatch within a week.

Distribution

North America

Economic Host(s)

A range of agricultural crops including cabbage, oilseed rape, Lucerne, tobacco and pea.

Symptoms/Signs

Young larvae feed on the underside of leaves, chewing irregularly sized holes. Mature larvae feed more voraciously and will feed on seed pods or developing flowers and bolls.

Generations:

3-4 (climate dependent)