The horse chestnut leafminer cameraria ohridella Deschka & Dimic (Lepidoptera, Gracillariidae) is an invasive species of unknown origin first observed and identified in Macedonia in 1984 (Deschka & Dimic 19g6). The species has subsequently invaded much of central and westem Europe over the last 20 years at an approximate rate of 60 km year This species almost exclusively develops on leaves of white-flowered horse chestnut, Aesculus hippocastanum L., and can cause extensive dam- age' resulting in premature defoliation of trees in the summer- some infestations have also been recorded on maples : Acer pla- tanoides and Acer pseudoplatanus , but these appear to be opportunistic intestations adjacent to heavily infested horse chest- nut trees' However, considering the pressure on the moth to find new host plants after having defoliated host chestnut trees, it is suspected that damage on Acer sp. will increase. As a conseguence, we have studied the possible impact of this pest on maples' across Europe' we have canied out surveys in the Balkans, SwiEerland and France to record c. ohridella infestations on A- pseudoplatanus, and to study the parasitoid complex on both maple and hors€ chestnut tree€. Molecular analyses are being canied orÎ to study the possible presence of host races.