Vegetable Weevil
Listroderes costirostris obliquus (Klug), Curculionidae, COLEOPTERA

DESCRIPTION

Adult - The female adult weevil is about 6.4 mm long with a short, stout snout. It is dull grayish-brown with a light V-shaped mark on the wing covers.

Egg - The egg is elliptical, 0.5 mm in diameter, and creamy white when first laid. It becomes black before hatching.

Larva - The pale green, legless larva has a dark mottled head and is about 1 cm long when fully grown.

Pupa - The pupa is pale yellow at first and later turns brown. It is similar in shape to the adult, with snout, legs and wing pads folded vertically along the body. It is about 7.9 mm long.


BIOLOGY

Distribution - The vegetable weevil, originally from South America, was first reported in this country in 1922. It now occurs in the Gulf and southern states and in Oklahoma, Arizona, and California. In North Carolina the vegetable weevil occurs throughout the state but is generally more common in the southern Coastal Plain.

Host Plants - The vegetable weevil feeds on a wide range of cultivated crops: turnip, carrot, collards, mustard, tomato, potato, tobacco, clary sage, and also a number of weeds.

Damage - Larval and adult vegetable weevils attack foliage and roots of a number of vegetable crops, often injuring seedlings or newly set plants. Plants attacked underground are usually large-rooted crops like carrot and turnip. When larvae feed on buds, growth may be stunted. Irregularly shaped holes in the leaves are indicative of this pest.

Life History - The adult vegetable weevil is active during fall, winter, and spring and aestivates (enters dormancy) during the summer in trash, leaves or grass at the edge of fields. Reproduction is parthenogenetic (no males, females lay eggs which develop into females) and some individuals may live 2 years. After coming out of aestivation, adults feed for several days to a month before depositing eggs on turnips or collards. Oviposition begins in fall and may continue into spring of the next year. Hatch occurs after an incubation period of 2 or more weeks depending on the temperature. Larvae feed on various crops and become full grown in 23 to 45 days. They then excavate earthen cells in the soil and pupate. Pupation, which may occur in spring or in fall and late winter, lasts from a few days to 2 weeks depending on temperature. Adults emerge from January to June. The length of time from egg hatch to adult emergence may vary from 1 to 4 months. There is one generation per year.


CONTROL

Cultivation in fall and winter is important in reducing populations. Insecticides are also available for control of the vegetable weevil. For specific recommendations, consult the current North Carolina Agricultural Chemicals Manual.

Return to AG-295 Table of Contents