Insects have a matchless capability to adapt, which is apparent from the beguiling diversity of insects, as well as in their notorious habit to invade our agro-ecosystems. As insects rely strongly on their sense of smell, such adaptive radiation and speciation events are generally accompanied olfactory adaptation. Yet, the neuroethological bases of olfactory adaptation remain largely elusive.The European corn borer (ECB), Ostrinia nubilalis, is a textbook example of pheromone polymorphism. The existence of two clearly differentiated pheromone strains intrigued the curiosity of the chemical ecologists, especially since these pheromone strains seem to be fixed to different host plants. One pheromone strain strongly prefers ancestral host plants such as hop and mugwort, whereas the other strain has shifted to maize since its introduction in Europe in the 16th century.We are close to completing the characterization of molecular and physiological changes underlying its radical shift in pheromone preference. Although, the shift in the olfactory circuitry underlying this dichotomy in host choice is unknown.I will characterize the olfactory component of this host plant divergence in the ECB using a multidisciplinary approach, including electrophysiology, chemical analysis peripheral neurophysiology, central neuroanatomy, bahvioral and field tests.The host shift of the ECB serves as an example of host shifts induced through human created ecological niches. In addition, concomitant with our study of how the olfactory circuitry accommodates shifts, I will identify hop, mugwort and maize volatiles that attract ECB, which can be useful in novel monitoring control strategies of this pest species.