In Canada, 78 of the most important weed species are introductions from Eurasia (Frankton and Mulligan 1970). Classical biological control aims to reduce the density of alien weeds below the economic threshold through introduction of specific herbivores from the native distribution area (Peschken 1979). During extended field surveys in central and southeastern Europe, the Commonwealth Institute of Biological Control established the root-mining tortricid Agapeta zoegana Haw. as a promising control agent for Centaurea diffusa Lam. and C. maculosa Lam., 2 important ranch weeds in southwestern Canada (Harris and Myers 1984) and the northwestern United States (Maddox 1982). Due to the limited host range and suitable climatic conditions this moth was chosen for introduction into North America (Müller et al. 1982; Müller 1984). We wish to report an attractant that may be used to monitor the establishment of this beneficial species in its new habita
