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Black Vine Weevil
David Keith, Extension Entomology Specialist
August 28, 2003
Pest Identification & Damage
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Black Vine Weevil Adult |
Common Name(s):
Black Vine WeevilScientific Name:
Otiorhynchus sulcatus (Fabricius), Coleoptera: Family Curculionidae. This insect, a pest of ornamental shrubs, is a native of Europe that was introduced into the U.S. It is considered a major pest of nursery trees, vines, shrubs and flowers. Plants such as Taxus, rhododendron and hemlock are attacked, primarily in the northern and eastern states and in Canada. This insect is closely related to the much smaller, but related species, the strawberry root weevil, (Linne).Identifying Characteristics for Damaging Stage(s):
Adult beetles are black, broad-snouted, about 1/2 inch long with parallel ridges that run along the wing covers and with patches of yellow hairs on the wings. Larvae are white, have a reddish brown head and while they resemble white grubs, they do not have legs. Larvae consume the roots of many shrubs and can damage as many as 100 kinds of plants.Damage/Nature and Symptoms:
The BVW is a “snout beetle” or weevil, equipped with chewing mouthparts, both in the adult and larval stages. While adults feed on leaves of various hosts, they do not commonly cause serious damage. Typical adult feeding appears as crescent-shaped leaf notches. It is the larval stage, however, that is the most destructive due to their habit of feeding on roots, which often kills the plants. In Ohio, this insect sometimes becomes very destructive in polyhouses where perennials are grown.
Distribution and Life Cycle
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Black Vine Weevil Larva |
Distribution:
Northern and Eastern United States and Canada.
Summary of Life Cycle:
This insect principally winters as a partially grown larva in the soil, but a few may pass the winter months as adults in homes. Most adults emerge in mid-June and begin to deposit eggs about 2 weeks later, around July 1. Each parthenogenetic, flightless female is capable of depositing up to 500 eggs in soil at the bases of host plants. Eggs hatch about 2 weeks after laying and larvae begin to feed on roots of host shrubs and trees. The most extensive damage occurs in late May and early June before the larvae pass into the pupa stage. There is usually just a single generation.
Management Methods:
The black vine weevil is very difficult to control because it has few natural enemies, is active mainly at night and most of the attack occurs below the soil surface.Inspection/Survey Methods:
Keep an eye on plantings, watching for feeding by adults, which appears as leaf notching. Look for activity at night with a flashlight when weevils are active and feeding. A piece of burlap laid at the bases of trees and shrubs will serve to trap weevils that hide under it during the day. Begin weevil surveillance early with a view toward early timing of treatments to prevent egg deposition.
Non-Chemical Management Strategies:
Survival of both eggs and larvae is greater if mulches are used, watering is reduced and if soils are allowed to dry out in July and August. Providing for adequate drainage around plantings near homes should help somewhat. Some success has been achieved in protecting potted plants by using entomopathogenic nematodes which attack the larvae. Keeping the soil moist after nematode release is important to enhance their effect.Chemical Management Strategies:
Successful chemical control is possible with very water-soluble, long residual insecticides. Treatment for adults should commence before egg laying, about 2-3 weeks after emergence. Drenching of potted plants has been effective in Ohio. Sprays for adults can reduce populations, but these must be applied frequently. Early applications are important to prevent as much egg laying as possible.For the latest information on available chemical controls, consult the Pesticide Selection Guide.
References:
Baker, W. L., 1972. Eastern Forest Insects. USDA Forest Service Misc. Pub. No. 1175, US Forest Service, 642 pp.
Klass, C., and W. T. Johnson, 1995. Black Vine Weevil. Cornell Cooperative Extension, Suffolk County. Http://www.cce.cornell.edu/suffolk/grownet/tree-insect/b...
Metcalf, C. L., W. P. Flint and R. L. Metcalf, 1962. Destructive and Useful Insects. 4th Ed. McGraw-Hill Book Co., New York NY. 1087 p.
Shetlar, D. J., 2000. Black Vine Weevil (and other root weevils). Ohio State University Fact Sheet. HYG-2016-95. Entomology http://ohioline.osu.edu/hyg-fact/2000/2016.html