Cabbage butterfly / leaf webber
Bigger, easier-to-spot caterpillars than diamondback moth — but their droppings can foul the developing head even when leaf damage looks moderate.
- Pest type
- Large defoliating caterpillar
- Attacks
- Leaves & developing head
- Worst in
- Vegetative to head-formation stage
- Main risk
- Defoliation + frass-fouled heads
Overview
Cabbage butterfly and leaf webber are large green or hairy caterpillars, clearly bigger than the small green diamondback moth caterpillar, that chew large ragged holes in cabbage and cauliflower leaves. Some also web leaves together as they feed, which is where "leaf webber" comes from.
Because these caterpillars are large, their droppings (frass) collect on and inside the leaves and the forming head, fouling it even where the visible feeding damage outside looks only moderate — so it is worth checking inside the head, not just the outer leaves.
How to identify it
- Larger green or hairy caterpillars, clearly bigger than the small green diamondback moth caterpillar, chewing large ragged holes in the leaves.
- Some caterpillars web leaves together as they feed, giving the "leaf webber" part of the name.
- Droppings (frass) collect on and inside the leaves and forming head, fouling it even where feeding damage looks moderate.
The damage it does
- Defoliation reduces the leaf area the plant needs to bulk up the head.
- Frass contamination of the developing head lowers its market quality even when the plant itself survives fine.
- Because the caterpillars are large, a few can still do a lot of visible damage quickly.
When to act
- Check the underside of leaves and inside the developing head regularly, since both feeding damage and frass build up there.
- Hand-pick as soon as caterpillars are seen — their size makes early action easy and effective.
- Spray only once damage crosses a noticeable threshold, since light feeding rarely justifies a chemical spray on its own.
Organic & cultural control
- Hand-pick the conspicuous caterpillars regularly — their large size makes this genuinely practical, unlike with smaller pests.
- Spray Bt (Bacillus thuringiensis), a caterpillar-specific biological spray that is gentle on natural predators and safe close to harvest.
- Clear old crop debris after harvest so caterpillars and pupae do not carry over to the next planting.
Chemical control
- A recommended insecticide once damage crosses a noticeable threshold across the field, not for occasional light feeding.
- Time any spray before heads have started to form tightly, so coverage reaches the caterpillars rather than being blocked by a closed head.
- Confirm the current recommended product and dose for cabbage/cauliflower with your local KVK.
Crops most at risk
Where this problem is called out in our crop guides — open a crop for the full package of practices.
Frequently asked questions
I see big ragged holes in my cabbage leaves and some webbing. What pest is this?
Large green or hairy caterpillars chewing big holes and sometimes webbing leaves together point to cabbage butterfly or leaf webber. These caterpillars are noticeably bigger than the small green diamondback moth caterpillar, which causes finer, more scattered damage.
Is hand-picking really enough for this pest?
Often yes, because the caterpillars are large and easy to see and catch — check the leaf undersides and the developing head regularly and pick them off. Spray only if numbers grow beyond what hand-picking can manage.
Why does the harvested head sometimes look dirty even when leaf damage looks minor?
The caterpillars’ droppings (frass) collect inside the developing head as they feed, which can foul it even when the visible leaf damage outside looks moderate. Check inside the head, not just the outer leaves.
Symptoms and control measures follow ICAR, KVK and state agricultural-university package-of-practices; any named chemical is a registered use. Always read the product label and confirm the dose for your crop and zone. editorial policy.