Several species of leaf miner are found in the UK on a wide range of crops but all produce the characteristic 'mines' within the leaf, in which the larvae feed. Adult feeding produces small discrete white spots (1mm diameter) on the leaves, usually on the upper leaf surface.
The larval stages inside the leaf can be controlled using parasitic wasps. Some leaf miner species are notifiable insect pests. Correct identification by PHSI (Plant Health and Seeds Inspectors) for any suspect insects is essential.