As its name suggests, the larvae of these insect pests eat away at the inside of leaves, causing tell-tale trails – or mines.
Female insects lay small eggs on leaves of apple, holly, chrysanthemum and numerous other plants. On hatching, the insect larvae tunnel into the leaves and feed between the two leaf surfaces. This creates clear trails or ‘mines’ in the leaf.
Leaf miners leave pale twisting tunnels under the surface of affected leaves. They are decoratively unsightly, but normally do little or no major harm to plants. However, the horse chestnut leaf miner has become a problem in recent years and causes significant damage.
Treatment and control
If feasible, squash the tunnel to kill the burrowing larvae or pick off affected leaves and burn them. Regular cultivation of the soil below the affected plant will allow feeding birds to reduce the population as they feed on the pupae.
It is very difficult to achieve good control of leaf miners with insecticides, as they are protected within the leaf. If plants become extensively attacked, depending on the plant, a systemic insecticide may help control them.