Common name: Cabbage webworm
Scientific name: Hellula undalis
Synonyms: Cabbage borer, Cabbage center grub, Cauliflower head borer, Imported cabbage webworm, Oriental cabbage webworm, Old world webworm, Striped cabbage heart caterpillar, Webworm cabbage (CABI, 2000).
Crucifers, watercress, radish
The feeding damage made by the larvae are the mined and/or bore leaves and bore stems. They feed first externally on the leaves and continue feeding into the terminal bud. Infested plants produced small heads and in severe cases, they do not form heads at all. The larvae feed beneath their protective webs made from the silken like threads that they form. The silken webs are found on the inner leaves' surfaces and stalks.
The cabbage webworm can be detected by their webs, frass, and other feeding debris produced while feeding.
Eggs are oval and creamy-white in color. These are laid in clusters from 28 to 214 eggs. The egg stage lasts from 2-5 days.
The larva has dark-brown or black heads. Its body is creamy-white with light pinkish-brown longitudinal stripes. It is about 1.2 to 1.5 cm when fully grown. The larval stage is about 6 to 18 days.
The pupa is contained inside a loose cocoon. It has a shining pale-brown color with a dark dorsal stripe. The pupal stage is about 4 to 20 days.
The adult is grayish-brown with pale-dusky hindwings. Each forewing has a prominent black spot and zigzagging light-brown lines. The central band between the lines is sometimes filled with darker-brown scales. The adult moth is capable of flying long distances. It occasionally migrates to areas outside its normal breeding range.