''Larinus planus'' is an

insect Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three pairs ...

of the

Curculionidae The Curculionidae are a family of weevils, commonly called snout beetles or true weevils. They are one of the largest animal families, with 6,800 genera and 83,000 species described worldwide. They are the sister group to the family Brentidae. T ...

("true" weevil) family. They are oval shaped, dark brown or black, and about long. While native to

Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...

, it is also common in

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...

. It feeds on floral buds, primarily of

thistles Thistle is the common name of a group of flowering plants characterised by leaves with sharp prickles on the margins, mostly in the family Asteraceae. Prickles can also occur all over the planton the stem and on the flat parts of the leaves. ...

, with the larvae stage being the most destructive to them. In North America, it has been used as a

biocontrol agent Biological control or biocontrol is a method of controlling pests, such as insects, mites, weeds, and plant diseases, using other organisms. It relies on predation, parasitism, herbivory, or other natural mechanisms, but typically also invo ...

. It is also known as ''Larinus carlinae''.

Description

The adult weevil is mostly dark brown or black, but has red-brown antennae. It is about long and oval shaped. The wing covers have light colored mottled hairs on them and appear pock-marked. The nose is long and narrow, with a pronounced curvature. Canada Thistle Bud Weevils (Subgenus Phyllonomeus) Mating

Canada Thistle Bud Weevils (Subgenus Phyllonomeus) Mating

The eggs are black and appear the size of a "pin-prick." Once hatched, the larva has a segmented white body with a brown head, and is "C" shaped.

Distribution

This weevil is

indigenous Indigenous may refer to: *Indigenous peoples *Indigenous (ecology), presence in a region as the result of only natural processes, with no human intervention *Indigenous (band), an American blues-rock band *Indigenous (horse), a Hong Kong racehorse ...

to southwest

England England is a country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe b ...

, as well as

Central Central is an adjective usually referring to being in the center of some place or (mathematical) object. Central may also refer to: Directions and generalised locations * Central Africa, a region in the centre of Africa continent, also known as ...

and

Eastern Europe Eastern Europe is a subregion of the Europe, European continent. As a largely ambiguous term, it has a wide range of geopolitical, geographical, ethnic, cultural, and socio-economic connotations. The vast majority of the region is covered by Russ ...

. It was accidentally introduced to

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...

and the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...

in the 1960s. The first published record is from

Maryland Maryland ( ) is a state in the Mid-Atlantic region of the United States. It shares borders with Virginia, West Virginia, and the District of Columbia to its south and west; Pennsylvania to its north; and Delaware and the Atlantic Ocean to ...

in 1971. It is now widespread throughout North America.

Biology

Adults emerge in the

spring Spring(s) may refer to: Common uses * Spring (season), a season of the year * Spring (device), a mechanical device that stores energy * Spring (hydrology), a natural source of water * Spring (mathematics), a geometric surface in the shape of a ...

, and begin feeding on thistle buds. They require buds ranging in size from 5-7mm. The insects mate when the temperature is at least , which is usually about 14-16 days after they emerge. The female deposits a single egg in each floral bud, and then seals it. After hatching, the larva feeds on the floral bud it is hatched in. In doing so, it destroys about 95% of the seed contents. Another brood of adults emerges in late

Autumn Autumn, also known as fall in American English and Canadian English, is one of the four temperate seasons on Earth. Outside the tropics, autumn marks the transition from summer to winter, in September ( Northern Hemisphere) or March ( Sou ...

. These adults spend the winter in plant litter, to emerge in the spring. ''Larinus planus'' prefers dryer ranges, but can also adapt to wetter locations. It does well in sunny areas with well drained soils.

Use as Biocontrol Agent

In Canada, it has been used as an agent of

biological pest control Biological control or biocontrol is a method of controlling pests, such as insects, mites, weeds, and plant diseases, using other organisms. It relies on predation, parasitism, herbivory, or other natural mechanisms, but typically also invo ...

against the

noxious weed A noxious weed, harmful weed or injurious weed is a weed that has been designated by an agricultural or other governing authority as a plant that is injurious to agricultural or horticultural crops, natural habitats or ecosystems, or humans or liv ...

Canada thistle ''Cirsium arvense'' is a perennial species of flowering plant in the family Asteraceae, native throughout Europe and western Asia, northern Africa and widely introduced species, introduced elsewhere.Joint Nature Conservation Committee''Cirsium a ...

(''Cirsium arvense''). It was subsequently evaluated in the United States as a biocontrol agent and distributed across a range of the

Great Plains The Great Plains (french: Grandes Plaines), sometimes simply "the Plains", is a broad expanse of flatland in North America. It is located west of the Mississippi River and east of the Rocky Mountains, much of it covered in prairie, steppe, an ...

in the

western United States The Western United States (also called the American West, the Far West, and the West) is the region comprising the westernmost states of the United States. As American settlement in the U.S. expanded westward, the meaning of the term ''the Wes ...

. In 2000, it was found feeding on ''

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 British Columbia east to Manitoba and south as far as the State of Durango ...

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

Colorado Colorado (, other variants) is a state in the Mountain West subregion of the Western United States. It encompasses most of the Southern Rocky Mountains, as well as the northeastern portion of the Colorado Plateau and the western edge of t ...

and eastern

Utah Utah ( , ) is a state in the Mountain West subregion of the Western United States. Utah is a landlocked U.S. state bordered to its east by Colorado, to its northeast by Wyoming, to its north by Idaho, to its south by Arizona, and to it ...

. Subsequent research determined that the weevil reduced seed production of the native thistle. It has also been found to have an adverse effect on the native and threatened ''

Cirsium pitcheri ''Cirsium pitcheri'', sometimes called Pitcher's thistle or dune thistle, is a species of thistle native to sand dune shorelines along the upper Great Lakes. It is native to Indiana, Illinois, Michigan, Wisconsin, and Ontario. It is listed by t ...

''.

References

{{DEFAULTSORT:Larinus planus Lixinae Beetles of Europe Beetles of North America Biological pest control beetles Insects used for control of invasive plants Beetles described in 1792