A Way to Distinguish Sex of Adult Hylobius Weevils in the Field

Abstract

The median depression on the last abdominal sternite is a useful character for distinguishing, in the field, the male from the female adult of all North American Hylobius species.Everett and Newsom (1964) used a midline depression or sulcus on the abdominal sternites to separate the sexes of the rice water weevil, Lissorhoptrus oryzophilus (Kushel), and other weevils that are not closely related to species of Hylobius in North America. The male of Hylobius abietis L., a European relative, is distinguished from the female by a saucerlilte depression on the last sternite (Anonymous 1952). Millers et al. (1963) state that the first and second visible abdominal sterna of the male H. rhizophagus Millers are concave, and the fifth has a slight median depression; the female sterna are convex.