Life cycle and appearance of Horse-chestnut leaf miner

The adult moth is 4-5 mm long and a rich brown colour with bright white chevrons edged with black. The larvae mine in horse chestnut leaves go to four (occasionally five instars) and their size varies form 0.5 mm in the firsts instar up to 3.5 mm in the fourth instar. The pupa is brown and is 2.9-4.5 mm long.

The horse-chestnut leaf miner overwinters in the pupal stage in a cocoon in dead leaves. The emergence of adults in spring occurs in April and May, depending on climatic conditions. After mating, each female may lay up to 180 eggs singly on the upper part of the leaflets. Females of the second and third generations lay eggs on all leaflet surfaces. Larval development lasts 25-35 days. First-instar larvae make only a small gallery. The second- and third-instar larvae develop a round mine of 4-7 mm diameter. The larva then goes through two spinning instars, which may or may not build a true cocoon in the mine. The percentage of larvae which spin true cocoons increases in each of the subsequent generations. Adults of the first generation emerge from mid-June to late-July. Cameraria ohridella has two to four generations a year, depending on the temperature conditions.