Cabbage loopers are pale green worms (light stripes down the back) reaching one and a half inches long that devour the leaves of cole crops (cole crops are cabbage, broccoli, cauliflower etc).
They can quickly skeletonize a plant leaving only the outlines of leaves if uncontrolled. And these are the “surprises” that inhabit the broccoli florets.
You’ll quickly figure out the “looper” part of the name because as it moves along the leaf, it doubles up in “loops” as it moves.
Cabbage loopers lay eggs that are greenish-white and are laid in single eggs on the upper surface of leaves. They overwinter as green or brown pupa attached to one side of a leaf (an excellent reason to clean up the garden in the fall) and hatch out in the spring.
Cabbage looper moth
CC BY 2.0, Image Courtesy
Control is fairly straightforward.
- The first is garden sanitation. By eliminating the overwintering pupa, you’ll reduce next year’s hatch. So clean up the garden in the fall.
- Bt (bacillus thuringiensis) is a bacteria that parasitizes the gut of caterpillars. It doesn’t kill them outright but does stop them from eating. Infected garden pests quietly go somewhere else and die. Bt is not harmful to other non-target pests, pets or humans. Click here for pricing and shipping
- Rotenone as a contact dust kills them instantly. Follow the directions on the label and do not breathe rotenone. Rotenone is not a good thing for humans even though it is organic and only is effective for 24 hours (sunlight deactivates it).
- Insecticidal soap works on cabbage loopers as well as most other pests. But it’s not as effective as other controls. You’ll have to thoroughly wet the leaves and flowering parts of the plant. Soap has no residual action and you have to hit them to kill them. Follow the label directions for repeat spraying (one spray will not get all these pests).
- You can also easily hand pick them if you’re not squeamish.
- They are dislodged by a strong jet of water as well but not killed and they will climb back up onto the plant.