''Lixus concavus'', commonly called the rhubarb curculio, is a species of

weevil Weevils are beetles belonging to the superfamily Curculionoidea, known for their elongated snouts. They are usually small, less than in length, and herbivorous. Approximately 97,000 species of weevils are known. They belong to several families, ...

Rhubarb Rhubarb is the fleshy, edible stalks ( petioles) of species and hybrids (culinary rhubarb) of '' Rheum'' in the family Polygonaceae, which are cooked and used for food. The whole plant – a herbaceous perennial growing from short, thick rhi ...

(''Rheum'' species) is a host, together with dock, sunflower, and thistle.Connecticut Agricultural Experiment Station. Accessed : 2010-07-21
/ref>

Characteristics

''L. concavus'' has a distinctive long snout and geniculate antennae with small clubs. The beetle is about half an inch in length, black, covered with yellow dust, and hibernates as an adult. Eggs are a yellow-white colour and oblong in shape; the legless larva is a grub, about 3/4 inch in length, with a brown head that usually bears an inverted, Y-shaped mark.

Life cycle

Gummosis on Rhubarb caused by Lixus concavus

The adult rhubarb curculio overwinters in leaf litter or other similar sites and appears in mid-May. The adult makes feeding and egg punctures in the crowns, roots, and stalks; a jelly-like sap exudes from the wounds as glistening drops of gum, often with extraneous material trapped within. The eggs laid in rhubarb do not hatch, but are killed by the sap or crushed by the developing tissues.Insect Diagnostic Laboratory. Accessed : 2010-07-21
/ref> ''Lixus concavus'' is able to complete its lifecycle in the stalks of curly dock,

sunflower The common sunflower (''Helianthus annuus'') is a large annual forb of the genus ''Helianthus'' grown as a crop for its edible oily seeds. Apart from cooking oil production, it is also used as livestock forage (as a meal or a silage plant), ...

s, and

thistle 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 ...

s; eggs are laid singly in cavities, created by feeding activity, and hatch within a week to 10 days. One grub usually develops per plant, the larva having burrowed through the stalk down to ground level, where pupation occurs after around nine weeks; the larva chews an exit hole for the adults before pupating. The pupa is whitish and measures 14–15 mm long. The head bears the long snout of the adult form. The abdominal segments are marked with short spines. The larva takes a few weeks to develop into an adult that feeds for a few weeks before seeking out a site to overwinter. The weevil has one generation per year. The adult weevil feeds upon the margins of the leaves besides puncturing the stalks; damage appears as distinct notches in the plant tissues.

Control

''L. concavus'' is usually present in fairly small numbers and can be handpicked and then destroyed. Removal of the other host plants, such as curly dock, wild dock, sunflower, and thistle, during midsummer, when the ''L. concavus'' larvae are still in them, may also help to reduce pest populations.Ohio State University Extension Fact Sheet. Accessed : 2010-07-21

Parasites and cannibalism

The

braconid wasp The Braconidae are a family of parasitoid wasps. After the closely related Ichneumonidae, braconids make up the second-largest family in the order Hymenoptera, with about 17,000 recognized species and many thousands more undescribed. One analysis ...

'' Rhaconotus fasciatus'' is the only recorded

parasitoid In evolutionary ecology, a parasitoid is an organism that lives in close association with its host (biology), host at the host's expense, eventually resulting in the death of the host. Parasitoidism is one of six major evolutionarily stable str ...

of the rhubarb curculio. As stated, only a single larva develops to maturity in hosts other than rhubarb; it is not uncommon, however, to find several young larvae in the stalk of a host plant, indicating that the larvae may be

cannibalistic Cannibalism is the act of consuming another individual of the same species as food. Cannibalism is a common ecological interaction in the animal kingdom and has been recorded in more than 1,500 species. Human cannibalism is well documented, bo ...

.Simply Kitchen Garden. Accessed : 2010-07-21.
/ref>

Distribution

''L. concavus'' is found throughout the

eastern United States The Eastern United States, commonly referred to as the American East, Eastern America, or simply the East, is the region of the United States to the east of the Mississippi River. In some cases the term may refer to a smaller area or the East C ...

west to

Idaho Idaho ( ) is a U.S. state, state in the Pacific Northwest region of the Western United States. To the north, it shares a small portion of the Canada–United States border with the province of British Columbia. It borders the states of Monta ...

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 its ...

, and

Texas Texas (, ; Spanish: ''Texas'', ''Tejas'') is a state in the South Central region of the United States. At 268,596 square miles (695,662 km2), and with more than 29.1 million residents in 2020, it is the second-largest U.S. state by ...

. In

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 to ...

, it is known from

Ontario Ontario ( ; ) is one of the thirteen provinces and territories of Canada.Ontario is located in the geographic eastern half of Canada, but it has historically and politically been considered to be part of Central Canada. Located in Central Ca ...

. It is found in the

United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the continental mainland. It comprises England, Scotland, Wales and ...

References

External links

The book of field and roadside: open-country weeds, trees, and wildflowers.
* * {{Taxonbar, from=Q6659968 Lixinae Beetles described in 1831