Nearctic walnut leafminers invade Europe: first Coptodisca lucifluella (Clemens, 1860) and now Coptodisca juglandiella (Chambers, 1874) (Lepidoptera, Heliozelidae)

The Nearctic leafminer of black walnut Coptodisca juglandiella (Chambers, 1874) was found in Hungary and reported as new for Europe. Larvae were found in leafmines on black walnut (Juglans nigra (L.)), white walnut (J. cinerea (L.)) and Arizona walnut (J. major (Torr.)); the latter two Juglans species are new host plant records for C. juglandiella. Mines of Coptodisca lucifluella (Clemens, 1860), another Nearctic invader, were found on leaves of bitternut hickory (Carya cordiformis (Wangenh.) K.Koch) and Caucasian wingnut (Pterocarya fraxinifolia (Lam). Spach.) (a new hostplant record), in addition to common walnut (Juglans regia L.). Interestingly, C. lucifluella is thought to have performed a host plant shift after its introduction into Europe, whereas C. juglandiella apparently did not. Coptodisca juglandiella has three generations in Hungary. The autumn generations of both species produced many more mines than the spring generations. One hymenopteran parasitoid specimen was reared from C. juglandiella. Larvae, mines and adults of C. juglandiella and C. juglandiella can be easily distinguished, differences are presented and illustrated. The genitalia of C. juglandiella are described for the first time.