Cabbage Worms

Cabbageworms are around 3 cm long and velvety green. The lopers are green and move like inchworms.

Cabbage Loper-KennethA. Sorenson-NC State University (top left), Cabbage worm-Clemson University (top right), Cabbage worm-University of Illinois (bottom)

Description
 The adults of lopers are white small butterflies (adults of the worm are brown). They lay their eggs on the leaves of host plants like cole crops, radishes and turnips. The adults of the loper are brown or green in colour.

Eggs (top left), Lifecycle (top right), Adult moth (bottom)-KennethA. Sorenson-NC State University

Damage
Large holes in leaves and inside plants which can kill the host plants. They appear in the garden in late spring and are active until mid fall. They hide in the crinkly curling leaves of vegetables. They are hard to spot on the leaves but they do leave dark green droppings on the leaves. They leave holes in the leaves so you know that they are present.

Size-backyardgardener.com

Damage on cabbage plant-KennethA. Sorenson-NC State University

Control
1) Hand pick
They are not easy to see on green plants, red cabbage however is an easy one. Sometimes they’re hiding inside the tender broccoli leaves. Look for signs that they are there and then you will be able to find them.
2) Use row covers
Make them out of light permeable material. There is some that you can buy.
3) Organic sprays
Bt (bacillus thuringiensis), safer’s soap and predatory insects (ladybugs, spiders, some flies and predatory wasps.).