to high moth mortality as the larvae compete for space and food. The moth is able to go through up to five generations each year, if the weather is hot and dry; on average in western Europe, the moth goes through three generations each year. The last generation of the year pupates for over six months so as to survive the winter. The pupae are extremely frost tolerant and have been recorded to survive temperatures as low as . This allows its populations to increase even after hard winters. The dead patches that the horse-chestnut leaf miner causes on leaves are similar to damage caused to horse-chestnut trees by the fungus Guignardia aesculi, but can be distinguished by the fungal infection often being outlined by a conspicuous yellow band which the mines lack. The pupae can be mistaken for pupae of the genus Phyllonorycter but can be distinguished because C. ohridella pupae do not have a cremaster and the first five abdominal sections have strong lateral spines on them. Distribution and dispersal Cameraria ohridella has now been found in Albania, Austria, Belgium, Belarus, Bosnia and Herzegovina, Bulgaria, Croatia, the Czech Republic, Denmark, England and Wales, Estonia, Finland, France, Germany, Greece, Hungary, Ireland, Italy, Kosovo, Latvia, Liechtenstein, Lithuania, Luxembourg, Moldova, Montenegro, the Netherlands, North Macedonia, Poland, Serbia, Romania, Russia, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and Ukraine. Although horse-chestnut occurs naturally mostly above the contours the moth does well in well-watered places such as parks in cities and at low elevation but not well in the hotter parts of Europe e.g. Spain. Probably aided greatly by vehicular transport, the moth has attained a very rapid dispersal rate across Europe of per year. Origin and epidemiology Cameraria ohridella was first noticed from outbreaks near Ohrid Lake, Yugoslavia in 1984, and was described as a new species by Deschka and Dimić in 1986. A likely Balkan origin for this moth was evidenced from a decrease in genetic diversity from natural towards artificial horse-chestnut stands that were planted around Europe since around 1600. This Balkan origin is further documented by numerous herbarium samples that date back to 1879. These include an outbreak which occurred in horse-chestnut specimens collected by F.K. Meyer in 1961 in Albania. Of the 30 known mitochondrial haplotypes for the species only three (known as A, B and C) have invaded the rest of Europe since 1989, and only A