Imported Cabbageworm

Pieris rapae

Imported Cabbageworm is treated as a species-level brassica caterpillar pest affecting cabbage, kale, collards, broccoli, cauliflower, mustard, and related plants. Larvae chew irregular holes and contaminate heads with green frass. Feeding is often concentrated on outer and wrapper leaves before moving into heads.

Identification

Velvety green larvae have a faint yellow dorsal stripe and move slowly. Adults are white butterflies with dark wing tips and one or two black spots. The relevant host or site is cabbage, kale, collards, broccoli, cauliflower, mustard, and related plants. Watch for white butterflies, then turn leaves for single eggs and small velvety larvae. Inspect head-forming crops before larvae enter tight folds.

Symptoms / Signs

Larvae chew irregular holes and contaminate heads with green frass. Feeding is often concentrated on outer and wrapper leaves before moving into heads. Fresh feeding carries live larvae or new frass; old scars persist.

Life Cycle / Process

Yellow spindle-shaped eggs are laid singly. Larvae pupate as an exposed green or brown chrysalis on plants or nearby structures. Larvae cause the damage, except grasshoppers, whose nymphs and adults chew. Control works best before larvae enlarge, bore, or seal themselves in silk.

Prevention

Inspect incoming plants and propagation material for eggs, small larvae, webbing, mines, or frass. Maintain crop records that link host stage with first egg or larval detection. Priority inspection target: cabbage. Focus species or category: Imported Cabbageworm.

Management / Control

Use row covers before butterfly entry, handpick eggs and larvae, conserve parasitoids, and apply Bt to small larvae when needed. Base action on active feeding, larval size, crop stage, and tolerance. Killing moths or butterflies after eggs are laid does not reverse existing injury. Recheck the same unit for fewer larvae and less new feeding.

Procedure Steps

1. Inspect the true feeding site and collect the smallest active larvae. 2. Record eggs, larval size, frass, feeding, and natural enemies consistently. 3. Apply Bt, virus, or a selective labeled insecticide while larvae are small and exposed. 4. Close the Imported Cabbageworm incident only after new injury stops.

Safety Notes

Protect food, seed, packaging, workers, and Myco-Patrons during inspection and treatment. Use tamper-resistant placements where baits or traps are necessary, and keep pesticides off food-contact surfaces. Structural or termite work may require a licensed Florida pest-control operator.