Plants of sunflower germplasm putatively resistant or susceptible to the red sunflower seed weevil, Smicronyx fulvus (Coleoptera: Curculionidae) were used to test the hypothesis that the volatile composition of these two types are different and may influence acceptance/rejection of sunflower germpalsm by S. fulvus. At least 13 volatile terpenoids were released by the different plant lines, with some varying in concentration according to plant line, head maturity, and time of day. Comparison between resistant and susceptible plant lines showed differences in concentrations of less abundant compounds (3E)-4,8-dimethyl-1-3-7-nonatriene, α-copaene, bornyl acetate, β-elemene, β-selinene and germacrene-D, indicating that, one or more of these compounds may be useful markers for resistance/susceptibility to S. fulvus. In behavioral binary choice bioassays, S. fulvus adults were attracted to sunflower heads, preferring R5.5 over R4 and R6 heads, and susceptible to resistant plants. Video recordings indicated both volatile and contact chemicals may be involved in host acceptance/rejection.