Field library

Diamondback moth

A small grey-brown moth whose green caterpillar is no longer than a grain of rice. The caterpillar scrapes the underside of the leaf and leaves a thin white window that later tears open into a hole. On a young crop it eats out the growing point and the plant never makes a head. It gets used to sprays very quickly, so the same medicine stops working after a few uses.

How to scout

Check the underside of the top leaves of ten plants. When you touch it the caterpillar wriggles backwards fast and drops down hanging on a fine thread, which is how you know it is this one.