Leaf Webber (Crocidolomia binotalis) – A Serious Pest of Crucifers

Distribution & Host Plants

• Found throughout India.
• Affects cabbage, radish, mustard, turnip, and other cruciferous crops.

Life Cycle

• Eggs: Laid in masses of 40-100 on leaf undersides. Hatch in 5-15 days.
• Larvae: Green, gregarious feeders, growing up to 2 cm.
  • Duration: 24-27 days (summer), 50-52 days (winter).
• Pupation: Occurs in soil or within webbed leaves and flowers.
  • Pupal period: 14-40 days (faster in summer).

Nature of Damage

• Caterpillars form a silken web around leaves.
• Leaves become skeletonized, reducing market value.
• Larvae feed on flower buds and pods, contaminating vegetables with excreta.

Economic Threshold Level (ETL) & Control Measures

• ETL: 15-20 moths per trap/day.
• Pheromone Traps:
  • 8-10 traps per acre from the 1-week crop stage.
  • Trap height: 1 ft above crop canopy for optimal catch.

Crop-Specific Damage

• Cabbage:
  • Skeletonization of outer leaves.
  • Larval damage in primordia/cupping stage, causing aborted or multiple heads.
  • Boreholes with frass and fecal matter in the head.
• Cauliflower:
  • Larval nibbling on growing tips causing blindness.
  • Discoloration of curd and larvae hidden beneath.
  • Boreholes in pods, leading to seed consumption.