Assemblages of mountainous day-active Lepidoptera in the Hruby Jesenik Mts, Czech Republic

Assemblages of diurnal Lepidoptera were collected from yellow water traps i n the subalpine belt of the Hruby Jesenik Mts; the trapping results were co mpared with four-years observational records. The method is efficient for q uick faunal surveys, but too destructive to be recommended for widespread u se. The traps captured 18 species and 3,948 butterflies and diurnal moths ( butterflies contributed to 11 species and 3,861 individuals in total). The numbers of individuals for species resident in the subalpine habitats were significantly higher than for migrant species. Sex ratios were consistently male-biased in resident species (probably due to higher flight activity of males), but not in migrants. The habitats at and near timberline were more diverse than the climatically extreme sites of arctic-alpine tundra. Two s pecies of satyrid butterflies, Erebia euryale and E. epiphron, were markedl y dominant in all the habitats under study; at the most extreme sites, they were virtually the only butterflies present. Forest clearing, which was th e only habitat not belonging to the subalpine belt, differed markedly from the rest of the study sites.