''Sphenophorus parvulus'', commonly known as the bluegrass billbug, is a species of beetle in the true weevil family ''

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. Th ...

''. It is found in North America, especially in the eastern United States. It is a pest of

Kentucky bluegrass ''Poa pratensis'', commonly known as Kentucky bluegrass (or blue grass), smooth meadow-grass, or common meadow-grass, is a perennial species of grass native to practically all of Europe, North Asia and the mountains of Algeria, Morocco, and Tuni ...

, corn and grain crops.

Taxonomy

Swedish entomologist

Leonard Gyllenhaal Leonard Gyllenhaal (3 December 1752 – 13 May 1840) was a Swedish nobleman, military officer and entomologist. Early life and ancestry Born on the Ribbingsberg manor in Västergötland in west Sweden, Leonard Gyllenhaal was son of Hans ...

described the organism in 1838. The species name is derived from the Latin adjective ''parvus'' "small".

Description

The adult bluegrass billbug is about in length, a third of which is the long, downward-curving snout or proboscis. The thorax bears deep puncture marks and the

elytra An elytron (; ; : elytra, ) is a modified, hardened forewing of beetles (Coleoptera), though a few of the true bugs (Hemiptera) such as the family Schizopteridae are extremely similar; in true bugs, the forewings are called hemelytra (sometime ...

have longitudinal grooves. These billbugs are usually some shade of brown, grey or black.

Distribution and habitat

The bluegrass billbug is native to North America. Its range extends from Ontario and Nova Scotia southwards to Idaho, New Mexico and Florida. It is commonest in the east of its range. It is found in grassland, including lawns, especially in association with

, as well as in corn and other grain crops.

Ecology

The adult beetle feeds on seedlings and tender young shoots of various grasses. It seldom flies, preferring to scramble among the crop plants. Although Kentucky bluegrass seems to be its favored host plant, it will also feed on

timothy-grass Timothy (''Phleum pratense'') is an abundant perennial grass native to most of Europe except for the Mediterranean region. It is also known as timothy-grass, meadow cat's-tail or common cat's tail. It is a member of the genus '' Phleum'', cons ...

, redtop grass,

maize Maize (; ''Zea mays''), also known as corn in North American English, is a tall stout grass that produces cereal grain. It was domesticated by indigenous peoples in southern Mexico about 9,000 years ago from wild teosinte. Native American ...

wheat Wheat is a group of wild and crop domestication, domesticated Poaceae, grasses of the genus ''Triticum'' (). They are Agriculture, cultivated for their cereal grains, which are staple foods around the world. Well-known Taxonomy of wheat, whe ...

and other small grain crops. Its feeding leaves a characteristic row of identical small holes across an unfolding leaf-blade. Breeding takes place in the late spring and there is a single generation. The female chews a hole in the stem of a grass plant and deposits a single egg inside. The developing white, legless,

larva A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects, some arachnids, amphibians, or cnidarians typically have a larval phase ...

hollows out the inside of the stem and feeds around the

root crown A root crown, also known as the root collar or root neck, is that part of a root system from which a stem arises. Since roots and stems have quite different vascular Vascular can refer to: * blood vessels, the vascular system in animals * vascular ...

. The plant often wilts, and can be distorted, weakened or even killed by the actions of adults and larvae. When fully developed, the larva

pupa A pupa (; : pupae) is the life stage of some insects undergoing transformation between immature and mature stages. Insects that go through a pupal stage are holometabolous: they go through four distinct stages in their life cycle, the stages th ...

tes, either in the stem or in the soil, and overwinters as an adult or as a pre-emergent adult inside the pupal case. Adult females may lay between 40 and 200 eggs over the course of one to three months.

Taxonomy

Description

Distribution and habitat

Ecology

References

Further reading