The objectives of this study were 1) to further clarify the status of the genera Polydrusus and Scythropus and 2) to redescribe and elucidate the morphology and distribution of the species of Scythropus in order to better facilitate their identification. Some 1650 specimens were used in the study and about 300 of these were critically examined for morphological variations of the head, beak, antennae, thorax, elytra, abdomen, integument, legs, genitalia, and eighth tergite and ninth segment of the male. Over one hundred genitalia were dissected and critically examined for good characters. The male genitalia were the most reliable single characters used in separating the species, however, other characters such as variations in antennae, color, vestiture, elytral patterns, integument color, and features of the head and legs were used to describe and further isolate them. A key has been constructed to facilitate more accurate identification of the species of Scythropus, and the distribution is given as well as the host plants when known. Seventy illustrations were made of the male genitalia, abdomen, pronotum, antenna, elytral vestiture, and the eighth tergite and the ninth segment of the males.