Larinus planus is a species of true weevil. It is used as an agent of biological pest control against the noxious weed Canada thistle (Cirsium arvense). The adult weevil is dark brown or black with light colored mottled hairs on its body. It is about 7-8 millimeters long. This weevil is native to Central and Eastern Europe. It was first accidentally introduced to the United States in the 1960s. The first published record is from Maryland in 1971. It was subsequently evaluated as a biocontrol agent in 1990 and redistributed across a wide range of the Great Plains and western States.