Last week we found our bed of leeks had been attacked by allium leaf miner.
We thought that other leek growers might like to check their leeks and burn all parts (including roots and rootball) of any infected plants (do not compost).
The page below shows the symptoms. You can see the symptoms and then the damage in the photos at the bottom – don’t cook them as the leeks are unusable.
The only practical control is to cover the crop, especially in the danger periods of March to June and September to November, with insect protective mesh or fleece, or grow them in a fleece tunnel. The second period is the most infectious one.