Imported cabbageworm

Imported cabbageworm biology & life cycle

Pupae overwinter and adults emerge about mid-May. Larvae hatch in the early June and begin feeding on the outer leaves, maturing in 2-3 weeks. Larvae leave the plants to pupate and a second set of adults emerges in late July and August. Two-three generations per year.

Identifying Imported cabbageworm

Imported cabbageworm: eggs

Eggs are spindle shaped and pale white when laid, gradually turning yellow.

Imported cabbageworm: larvae

Larvae grow to a length of 30 mm within two weeks. They are leaf green in colour with a thin orange stripe down the middle of the back and an irregular stripe along each side. Larval feeding damage is characterized by irregular holes chewed in the leaves.

Imported cabbageworm: Pupae

Pupae are attached to vertical sufaces by a single loop of silk. They are pale green and 15 mm long.

Imported cabbageworm: adult

20 mm in length with a wingspan of 30-50mm. The wings are creamy white in colour with black tips on the forewings.

Imported cabbageworm: management

The spring generation causes little damage. The presence of large numbers of adults in July and August indicates a need for closer inspection of fields.