As part of the on-going evaluation of different systemic insecticides for prophylactic treatment of the Asian longhorned beetle, Anoplophora glabripennis (Motschulsky) (Coleoptera: Cerambycidae), responses of adult beetles to different doses of four neonicotinyl insecticides were studied in laboratory. Adult beetles were provided with twigs or leaves of host trees treated with different concentrations of the four insecticides to evaluate the efficacy of the insecticide. The actual levels of individual insecticides in twigs and/or leaves were analyzed, and these levels were plotted against the applied concentration of these insecticides to determine the relationship between the two. The LC₅₀ values for detected level of each insecticide in twigs to adult beetle for 24h, 48h, and 72h were determined. The results indicate that mortality of adult beetles resulted not only from the oral and contact poison, but possibly also from the antifeedant effect of these insecticides.