Pest · Broccoli and cabbages
Cabbage white caterpillars: where they are eating
Pieris brassicae · Pieris rapae
The caterpillars of two white butterflies (large white and small white) eat the leaves of brassicas. We fly and mark the zones with most leaf damage; eggs and small caterpillars can only be seen on foot.
We have not flown this problem ourselves yet. We work it out with you, on your field.
The problem
Caterpillars that leave only the veins
The caterpillars eat the leaf until only the veins are left, and their droppings foul the heart and the head, which loses value. The large white lays yellow egg clusters on the underside of the leaf, and its caterpillars feed together, often at the edges of the field.
Attacks normally run from spring to autumn. Excess nitrogen, which gives leafy plants, and repeating brassicas without rotation favour them.
How it works
A flight to know where to look
1
We fly
When there is already eaten leaf somewhere.
2
We send you the map
The zones with most eaten leaf. The caterpillars are on the underside of the leaf and cannot be seen from the drone; you see the damage once it is large.
3
You check
The underside of the leaves, in those zones. Agree with your adviser the threshold at which to act.
To know when to act, talk to your adviser; the map shows where the damage is.
Where it shows up
Where it appears
- Broccoli
- Cauliflower
- Cabbage
What farmers ask us
Cabbage white caterpillars: field questions
How do I recognise the eggs?
Those of the large white are yellow, in clusters, on the underside of the leaf. The small white lays them singly and they are barely visible.
Does it have natural enemies?
Yes. A small parasitic wasp, Cotesia glomerata, parasitises the caterpillars. Broad-spectrum insecticides kill it too.
Does the drone see the caterpillars?
No. It sees the eaten leaf once the damage is noticeable, and it cannot tell this caterpillar from others that also eat leaf.
Know someone this would help?
Send them this page. If they have cabbage white caterpillars in their fields, you save them some searching.