Cabbage Borer (Cabbage Webworm)

📖 Description

Cabbage Borer or Cabbage Webworm (Hellula undalis) is an important pest of cabbage and other brassica vegetables across the Indian subcontinent, particularly severe in cabbage and cauliflower belts of Himachal Pradesh, Jammu & Kashmir, Uttarakhand, West Bengal, Odisha, Karnataka and Tamil Nadu. The larva is distinctive — it webs together leaves on the cabbage head with silk, creating a characteristic nest within which it bores into the head and stem. The webbing provides protection from natural enemies and insecticide contact, making control difficult unless webs are mechanically removed before spraying. Beyond direct boring damage, the webbed nests trap moisture and create conditions favourable for secondary bacterial and fungal infection, accelerating head decay. The pest is most severe in late-planted cabbage (October-January plantings) when temperatures are favourable for larval development — early plantings (September) typically escape peak pressure. IPM with mechanical removal of webbed nests (the single most effective control measure), Bt applications against exposed larvae, light trapping of adults, and conservation of native parasitoids (Apanteles) provides effective control. The pest is particularly difficult to control in cabbage because (a) the head protects larvae from insecticide contact, (b) webbing further shields larvae, and (c) larvae bore deep into the head where contact insecticides don’t reach. Systemic insecticides and Bt applications against early instars before they enter the head are the most effective chemical control measures.