Diamondback Moth

The most destructive pest of brassica crops (cabbage, cauliflower, broccoli, kale) worldwide. Diamondback moth (DBM) is estimated to cost the global agriculture sector $4-5 billion annually. It is the first insect pest known to have developed resistance to Bt (Bacillus thuringiensis) in the field, and has documented resistance to virtually every insecticide class used against it.

Adults are small, slender, gray-brown moths (8-10 mm) with a distinctive diamond-shaped pattern of pale markings on the back when wings are folded (hence the name). Larvae are small (10-12 mm), pale green, cigar-shaped caterpillars that wriggle violently when disturbed and drop from the plant on a silk thread.

• 1

  Larvae wriggle violently and drop on a silk thread when disturbed — highly characteristic

• 2

  Diamond pattern on folded moth wings is diagnostic (use hand lens)

• 3

  Larvae are pale green, cigar-shaped, smaller (10-12 mm) than other cabbage caterpillars

• 4

  Window-paning (transparent patches in leaves from young larvae feeding from one side) is typical DBM damage

• 5

  Place pheromone traps (DBM-specific lures) to confirm species and monitor moth activity

• Irregular holes in leaves, particularly between veins (window-paning from young larvae)

• Small green caterpillars on leaf undersides that wriggle and drop on silk when disturbed

• Severe defoliation of outer wrapper leaves in cabbage

• Damage to cabbage heads from larvae feeding between head leaves

• Contamination of broccoli and cauliflower florets with larvae — causing market rejection

Diamondback Moth can attack 4 crop species.