NATIVE RANGE: Balkan

FIRST FINDING IN SLOVENIA: 1994

PATHWAYS: hitchiker, secondary spontaniously spreading

POSSIBLE TO FIND: April – September

FLIGHT SEASON OF ADULTS: April – September

DESCRIPTION: A small moth with an overall length of 3–5  mm and a wingspan of 7–8 mm. The wings are brown with transverse white and black stripes and fringed edges. Females lay their eggs along the lateral leaf veins on the uppersides of Horse-chestnut (Aesculus hippocastanum) leaves. The first instar caterpillar enters the middle layer of the leaf where it feeds on the tissue between the upper and lower epidermis. In this way, a mine is created between two neighbouring veins. Fully grown caterpillars measure up to 5 mm long. Initial leaf damage becomes visible in May and damaged leaves dry and are shed prematurely. Horse-chestnut leaf-miners overwinter as pupae on fallen leaves.

HABITAT: Urban areas: avenues of street trees, parks and gardens where horse-chestnuts are planted.

STATUS: Widespread and common throughout Europe.

SIMILAR SPECIES: There are several similar species in the family of leaf blotch miner moths (Gracillariidae), which, however, exploit different larval host plants. The fungus Guignardia aesculi causes similar-looking damage on horse-chestnut trees.

SOURCE: Field Guide to Invasive Alien Species in European Forests