Examination with a binocular microscope of adults of Rhyssomatus subtilis Fielder (Coleoptera: Curculionidae) revealed distinct differences between the sexes in the foreleg, which permits their differentiation with complete accuracy. In the female the profemual process is weak, subacute, angulate and the protibia has an uncus and mucro. In the male the profemur process is strong, curved, subacute, tooth-like and lacks an protibia uncus.
