Outbreaks of Lymantria dispar in Russian forests during the 1990s

Lymantria dispar is one of the most widespread defoliators of deciduous and larch forests in Russia. Its outbreaks regularly occur in different regions of the country and cover huge areas from oak forests of the northern Caucasus and birch forests of the southern taiga of European Russia to larch forests of Siberia and broad-leaved forests of the southern Far East of Russia. Preferred host plants, flying capacity of females and neonate caterpillars, preferred places for egg laying, major factors of mortality and other characteristics vary considerably between different populations of the pest, and four geographical populations can be distinguished. The population dynamics of the pest in the 1990s and the increase in its area of distribution are analysed on the basis of survey data.