Sitona is a large genus of weevils in the family Curculionidae, native to the Nearctic and Palaearctic regions. More than 100 species have been described. Sitona is easily distinguished from related genera by flat, recumbent scales on the mandibles, by the absence of an oval scar on the mandibles, by short and broad rostrum with a deep, longitudinal, median groove, and by dense scales on the body.
They are phytophagous, with larvae feeding exclusively on plants of the family Fabaceae. Several species of Sitona are important agricultural pests of legumes, especially in its native regions and introduced populations in South Africa, Australia and New Zealand. It is likely that the larvae of Sitona feed on the nitrifying root nodules.
Description taken from Wikipedia: http://en.wikipedia.org/wiki/Sitona