The research objective of this study was to develop a pheromone-based detection system for the nun moth, Lymantria monacha (Linnaeus), an important defoliator of spruce, Picea A. Dietrich, and pine, Pinus Linnaeus (Pinaceae), forests in central Europe. In northeastern Germany, comparative analyses of rubber- and polyurethane-based dispensers impregnated with a 20:20:1 blend of (±)-disparlure (cis-7,8-epoxy-2-methyloctadecane), (±)-monachalure (cis-7,8-epoxy-octadecane), and 2-methyl-Z7-octadecene revealed that polyurethane-based dispensers afforded higher captures of male L. monacha. Species specificity and optimal dose of the pheromone dispenser were tested in deciduous rather than coniferous forests in central Europe to better reflect nonhabitat settings, such as North American ports, in which detection surveys would be conducted. Baiting Unitraps with 2, 20, 200, or 2000 μg [based on (±)-disparlure] of the L. monacha volatile blend resulted in increasing, species-specific captures of male L. monacha with increasing volatile dose. (±)-Disparlure, previously used for detection of L. monacha, tested at the same four doses indiscriminately attracted male L. monacha and male Lymantria dispar (Linnaeus). Polyurethane-based dispensers loaded with at least 200 μg of the L. monacha volatile blend are recommended for sensitive detection surveys of L. monacha in North America.