The explosive expansion of the lime leaf miner in Europe: invading the Netherlands?
A recent find of Phyllonorycter issikii at Schoonrewoerd, in the province of Zuid-Holland, implies that Ph. issikii is expanding in The Netherlands. Previous finds were restricted to the southern part of the province of Limburg, near the Belgian and German border, where the species was first recorded in 2009. The westward expansion fits with that of the species throughout Europe. Phyllonorycter issikii feeds on lime trees (Tilia) and has two generations per year with different forms: an aestival and autumnal form. There is some variation in the aestival form, with more clearly marked individuals closely resembling Ph. corylifoliella externally, and others less clearly marked and more easy to identify. The autumnal form is darker and lives through the winter. The prime method for observing the species, is looking for the typical leaf-mines on lime trees. Although the expansion of Ph. issikii is just as explosive as that of the horse-chestnut leafminer (Cameraria ohridella), there is significantly less damage to the host plants and the mines of Ph. issikii do not cause discolouration of the leaves.