Pieris Brassicae - Life Cycle and Foodplants

Life Cycle and Foodplants

The female lays batches of 20 to 100 yellow eggs on plants in the cabbage family and can be a pest on food crops. They seem to have a preference for cultivated varieties of Brassica oleracea such as cabbage and brussels sprouts. The caterpillars are yellowish green with yellow lines and black spots and feed in groups in plain view on the leaf surface. They gain protection from predators by possessing distasteful chemicals. It has once been reported that these chemicals were mustard oils from glucosinolates in the foodplants, but this appears to be a myth since Pieris caterpillars actually suppress the formation of mustard oils (see glucosinolate). Despite their chemical defense, large numbers are sometimes lost to the parasitic wasps such as Apanteles glomeratus, whose females attack clusters of newly hatched caterpillars. The chrysalis is also yellowish pale green with black spots. The species over-winters as a chrysalis. It has two broods in a year, the first is on the wing in May and June and the second in August.

• Eggs

• Caterpillar

• Pupa

• Adult on Buddleja davidii