Cabbage worm is one of the most common pests in the winter season. They cause a lot of damage to plants and reduce the yield by 20-30%. It also infects the other cabbage vegetable family such as cauliflower, broccoli, kale and etc. Infection can be seen at any stage of the life cycle.
Cabbage Worm Identification.
Eggs: Tiny, white to yellowish colored, bullet-shaped, ribbed eggs usually laid singly, on end. Solo, small size, white or yellow, Long oblong-shaped. You can find them on the inner side of the leaves.
Larvae: Velvety green caterpillars with a single yellow stripe down the center of the back, and yellow spots or a broken yellow line along each side. About 1 1/4" long in the final instar stage.
Pupae: Chrysalis about 1" long with one dorsal and two sides "fins." Color varies, but usually matches background: yellow, grey, green, brownish are common.
Adults: Butterfly with 2" wingspan. Wings are white on top, usually with black tips and 2 or 3 black spots, and yellowish underneath.
Host plant - cauliflower, collards, kale, turnip, and radish, cabbage, broccoli, Brussel sprouts, etc., and many related weeds.
Cabbage Worm Damage.
Adult Butterfly - Cause no damage as they feed on nectar.
Larval - feeding initially produces small, smooth feeding holes in leaves, which soon enlarge until the entire leaf is consumed, leaving only the midrib. Larvae sometimes bore into heads.
Large amounts of dark green faecal pellets will be scattered on or beneath the plants.
You can see dark green faecal pellets on the surface of the plant's leaves.
Control/Prevention for Cabbage Worms.
1. Manually Remove (handpick) - Inspect your pants frequently. At least 2 to 3 checking per week. As soon as you show any insect just throw out and check both sides of the leaves.
2. To control the adult butterflies you can put a yellow sticky trap in the field in between some distance. It will be helpful for other insects.
3. Spraying with Bt (Bacillus thuringiensis var. kurstaki) every 1 to 2 weeks will also help control cabbage family pests. Sevin also is effective. And, the few pests that remain on vegetables can be washed out after harvest using water and a small amount of detergent or other surfactants.
4. Row Covers- Use floating row cover (FRC)to prevent egg-laying( FRC is a white gauze-like material .It is used to cover individual plants so that adult butterflies are unable to lay eggs).
5. Short duration cabbage varieties sustain less damage.
6. Cabbage Moths Decoy-Cabbage moths are territorial and will stay away if there are other cabbage whites around! Thus, some gardeners have success in deterring them by placing decoy or dummy white butterflies around their garden beds.
7. If per crop two caterpillars are observed then spray with B.T@10 gm/10 Ltr water in the evening time. After that take neem ark@40 gm/Ltr spray. In case of high infestation take spray of Thiodicarb 75WP@40 gm/15 Ltr water.
8. Crop rotation with Turnip, rutabaga,