Black Vine Weevil
Otiorhynchus sulcatus (Fabricius), Curculionidae, COLEOPTERA


DESCRIPTION

Adult -The oblong black vine weevil is 10 to 11 mm long and has a short snout. The elytra possess many rounded tubercles, each with a short seta. The body is blackish brown; the antennae are black and slightly pubescent; and the head is smoother than the thorax (Color Plate 2J).

Egg -The egg is approximately 0.7 mm in diameter, with a smooth, shiny surface. It is white when first deposited but becomes brown as it ages.

Larva -As the legless larva matures, thickening thoracic segments cause its body to become curved. The fully grown larva is dirty white with a brown head.

Pupa -The pupa is white with prominent dusky spines on the head, abdomen, and legs.


BIOLOGY

Distribution -The black vine weevil has the name "vine" in its common name because it was first recognized as a pest of grapes in Germany in 1934. About 1910 the beetle was found in Connecticut and has since become a serious ornamental pest in southern Canada and the northern United States.

Host Plants -Many herbaceous and woody plants have been listed as hosts for the black vine weevil. Some of the preferred woody hosts include hemlock, rhododendron, and yew.p> Damage -Black vine weevil larvae can stunt the growth of a plant by feeding on the roots. Larger roots are stripped of their bark or girdled, or they have notches chewed out of them. The adult weevils chew the edges of the leaves, cut off the tips of needles, or devour entire needles (Color Plate 2J). The interior, older foliage is preferred to the terminal growth.

Life History -Black vine weevils overwinter as mature larvae or as pupae. However, a few adults also survive the winter to feed and deposit eggs during a second season. This weevil is parthenogenetic. Although one female was recorded as laying 863 eggs, the average number of eggs deposited by each female is probably about 200. During the preoviposition period, which lasts about 45 days, the adults feed most extensively. The longevity of the adult usually ranges from 90 to 100 days. Eggs, deposited in the soil and leaf litter, hatch in 2 to 3 weeks. Initially the young larvae feed on rootless; but after the third molt, the larvae move to the larger roots. During their development, the larvae molt five or six times within earthen cells in the soil constructed by the larvae prior to molting. After a quiescent prepupal stage that lasts from 3 weeks to 8 1/2 months, the larvae pupate. Three weeks later, adults emerge. Adults feed at night and drop from the plant, feigning death when disturbed. These weevils cannot fly; so they must be carried or must crawl to uninfested areas.


CONTROL

For specific chemical controls, see the current state extension service recommendations.

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