Larinus planus is a species of true weevil

Curculionidae

Curculionidae is the family of the "true" weevils . It was formerly recognized in 1998 as the largest of any animal family, with over 40,000 species described worldwide at that time...

. It is used as an agent of biological pest control

Biological pest control

Biological control of pests in agriculture is a method of controlling pests that relies on predation, parasitism, herbivory, or other natural mechanisms...

 against the noxious weed canada thistle

Cirsium arvense

Cirsium arvense is a species of Cirsium, native throughout Europe and northern Asia, and widely introduced elsewhere. The standard English name in its native area is Creeping Thistle.-Alternate names:...

 (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

Central Europe

Central Europe or alternatively Middle Europe is a region of the European continent lying between the variously defined areas of Eastern and Western Europe...

 and Eastern Europe

Eastern Europe

Eastern Europe is the eastern part of Europe. The term has widely disparate geopolitical, geographical, cultural and socioeconomic readings, which makes it highly context-dependent and even volatile, and there are "almost as many definitions of Eastern Europe as there are scholars of the region"...

. It was first accidentally introduced to the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 in the 1960s. The first published record is from Maryland

Maryland

Maryland is a U.S. state located in the Mid Atlantic region of the United States, bordering Virginia, West Virginia, and the District of Columbia to its south and west; Pennsylvania to its north; and Delaware to its east...

 in 1971.

It was subsequently evaluated as a biocontrol agent in 1990 and redistributed across a wide range of the Great Plains

Great Plains

The Great Plains are a broad expanse of flat land, much of it covered in prairie, steppe and grassland, which lies west of the Mississippi River and east of the Rocky Mountains in the United States and Canada. This area covers parts of the U.S...

 and western States

Western United States

.The Western United States, commonly referred to as the American West or simply "the West," traditionally refers to the region comprising the westernmost states of the United States. Because the U.S. expanded westward after its founding, the meaning of the West has evolved over time...

.

In 2000, it was found feeding on Cirsium undulatum

Cirsium undulatum

Cirsium undulatum is a species of thistle known by the common names wavyleaf thistle and gray thistle. It is native to much of central and western North America from Canada to Mexico, and present outside of its native range as an introduced species. It is widespread and found in many habitat types....

var. tracyi, a sparsely distributed thistle native to western Colorado

Colorado

Colorado is a U.S. state that encompasses much of the Rocky Mountains as well as the northeastern portion of the Colorado Plateau and the western edge of the Great Plains...

 and eastern Utah

Utah

Utah is a state in the Western United States. It was the 45th state to join the Union, on January 4, 1896. Approximately 80% of Utah's 2,763,885 people live along the Wasatch Front, centering on Salt Lake City. This leaves vast expanses of the state nearly uninhabited, making the population the...

. Subsequent research determined that the weevil reduced seed production of the native thistle.