The alfalfa weevil is one of the primary insect defoliators of alfalfa. Thought to be of Asian origin, the alfalfa weevil was introduced into the United States from southern Europe. First discovered in 1904 in Utah, it is now present in all 48 mainland states. Annually, insect pests of alfalfa, including the alfalfa weevil and potato leafhopper, cause hundreds of millions of dollars in losses. Though difficult to estimate, these same insects are estimated to reduce yields by 10 to 15% annually (forage quality not taken into account). Introduced biologicalcontrol agents and natural enemies have reduced alfalfa weevil populations in many areas, though it continues to be a sporadic pest of alfalfa.