The black vine weevil, Otiorhynchus sulcatus, is about 3⁄8 inch long and has a short snout. The thorax and wing covers are bumpy. The body is blackish brown; the antennae are black. The egg is smooth and shiny. It is white when first deposited but becomes brown as it ages. The legless, white grub grows to 1⁄2 inch long. Its body is curved with a brown head. The pupa is white with tiny spines on the head, abdomen and legs.
The black vine weevil has the name "vine" in its common name because it was first recognized as a pest of grape vines in Germany in 1934. In 1910, the beetle was found in Connecticut and has since become a serious ornamental pest in southern Canada and the northern United States. It is found in the Mountains and upper Piedmont of North Carolina where black vine weevils feed on azalea, euonymus, hemlock, hosta, rhododendron, and yew as well as many other herbaceous and woody plants.
Black vine weevil larvae stunt or kill plants 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. Foliage is preferred to terminal growth.
Black vine weevils overwinter as mature larvae. However, a few adults also survive the winter to feed and deposit eggs during a second season. This weevil is parthenogenetic (no males). 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 four weeks, the adults feed extensively. Adults usually live 90 to 100 days. Eggs, deposited in the soil and leaf litter, hatch in two to three weeks. Initially, the young larvae feed on rootlets; 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.
After a quiescent prepupal stage lasting three weeks to 81⁄2 months, the larvae pupate. About 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 of black vine weevils can be directed at adults as they first emerge on favored host plants (rhododendron, hosta, euonymus). Pesticides should be applied thoroughly to kill weevils on the plants and on the media or soil surface where the weevils hide during the day. Examine host plants frequently in late May and early June for fresh feeding damage.
A 1997 study in California showed a great reduction of black vine weevil in commercial planters using parasitic nematodes, Steinernema feltiae (327/inch2) or Heterorhabditis bacteriophora (474/inch2). The use of nematodes could be a viable alternative to chemicals, especially in sensitive public areas. Pesticides may be applied to the media or soil surface as a drench to control black vine weevil larvae. Imidacloprid (Merit, Marathon) can be used as a soil injection or drench against larvae. Scimitar & Demand (Oregon study) and Talstar (Ohio study) are effective when adults are present. Aloft may also be an effective product. Apparently, carbaryl (Sevin), malathion and isofenphos (Oftanol) are not effective for black vine weevil control. The standard Orthene is felt to be effective, but has shorter residual than the pyrethroids.
In Ohio, they found that adults begin to emerge in late May when black locust is blooming and recommend the first application soon thereafter when multiflora rose is in mid-bloom. They found adult emergence to be fairly synchronous (based on presence of pupae in the soil), peaking in mid-June and being largely done by July 4, with a tail distribution of stragglers emerging until mid-July. Timing sprays with bloom periods in North Carolina should be expected to hold. Use three sprays at three week intervals. For labeled pesticides, see the North Carolina Agricultural Chemicals Manual under the headings: Trees and Woody Ornamentals, Plant: Any, Black vine weevil.
- Black Vine Weevil, Controlling a Major Nursery and Landscape Pest. Gill, S. and P. Shrewsbury. 2013. IPM for Commercial Horticulture, University of Maryland Extension Fact Sheet FS-805.
- Black Vine Weevil, Otiorhynchus sulcatus. Hoover, G. A. 2000. College of Agr. Sci. Cooperative Extension, PennState.
- Insects and Related Pests of Shrubs
- Extension Plant Pathology Publications and Factsheets
- Horticultural Science Publications
- North Carolina Agricultural Chemicals Manual
- North Carolina Cooperative Extension
For assistance with a specific problem, contact your local Cooperative Extension Center.
Publication date: Nov. 1, 2003
Revised: Sept. 11, 2019
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