Horse chestnut leaf miner

Systematic position: The horse chestnut leaf miner (Cameraria ohridella) belongs to the order Lepidoptera and the family Gracillariidae. As an invasive moth species, it has spread rapidly across European and neighboring regions, becoming one of the most significant pests affecting ornamental chestnut trees.

Host plants: The primary host for this pest is the horse chestnut tree (Aesculus hippocastanum). While it shows a strong preference for this species, it may occasionally infest other members of the Sapindaceae family, causing severe aesthetic and physiological damage to urban landscapes and forest plantations.

Biology and life cycle: The pest overwinter as pupae within fallen leaves on the ground. During spring, the adult moths emerge to lay eggs on the upper surface of the leaves. Depending on climate conditions, the insect can complete three to four generations per year, leading to massive populations by mid-summer.

Nature of damage and harmfulness: Larvae mine the leaf tissue, feeding on the parenchyma between the epidermal layers. This creates brownish blotch mines. As the infestation progresses, leaves lose their ability to photosynthesize, curl up, and fall off prematurely. Severely affected trees may show signs of stunted growth and late-season reflowering.

Protection measures: Effective management relies on an integrated approach:

• Sanitation, involving the removal and destruction of infested leaf litter;
• Systemic insecticide treatments or trunk injections to reach larvae inside the mines;
• Use of pheromone traps for monitoring and reducing the density of adult males;
• Promoting biodiversity to encourage natural parasitoids and predators.