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Black vine weevil

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Common name:  Black vine weevil

Scientific name:  Otiorhynchus sulcatus

Hosts:  While able to feed on a wide range of herbaceous and woody ornamentals, the black vine weevil does the most damage to yews and rhododendrons. It will also attack strawberry, blackberry, blueberry, and cranberry plants, as well as forsythia, and euonymus.

Black vine weevil can cause damage to susceptible plants at both the adult and larval stages of its life cycle. The larval feeding at the root system does the real damage, with foliar feeding by adults being mostly cosmetic. This insect is found throughout a large part of North America.

The damage produced by the adult black vine weevil is usually not serious. It consists of U-shaped or semi-circular notches along the edges of the leaves or needles. If there are many notches on most of the plant foliage, it is likely that the roots are also severely damaged by larval feeding. The larval stage does serious damage by consuming roots. As a result of the larval feeding, the foliage of infested plants will turn yellow or brown, and can wither or otherwise show signs of poor growth. If left uncontrolled, a severe infestation may ultimately kill the host plant.

The black vine weevil has fused wings and can only move from plant to plant by walking or by being carried in infested plant containers or root balls. Therefore, an infestation is relatively slow to spread.

Black vine weevil has one generation per year. It overwinters in the soil as partially grown larvae. Larvae are C-shaped grubs, white with brownish heads, and approximately 1/2 inch in length when fully developed. In spring, after a short feeding period, the larvae pupate into adult weevils (beetles with snouts). The adults emerge from the soil from late spring into mid-summer (generally late May into July). The adult weevils are black to brownish-black, hard-shelled insects, generally 3/8 inch long, with ill-defined yellowish spots and an obvious snout. Their wings are fused together, making them incapable of flight.

The adult black vine weevil is nocturnal. During the day, the weevil hides in dark places on the stems of dense plants or in the ground litter and mulch beneath the crown. At night, the weevil feeds on foliage, cutting a characteristic U-shaped notch in the leaf margins.

All the adult weevils are female and are able to lay eggs without mating (parthenogenetically).  Eggs are laid during July and August in the soil beneath the host plants on which adults have been feeding. As many as 200 eggs are laid over a two to three week period. Once the eggs hatch in mid-summer, the larvae work their way through the soil at the base of the host plant and feed on the small roots and the bark of larger roots. This feeding takes place from the time the eggs hatch through the fall.

Management of the black vine weevil is possible if symptoms are recognized and treated early. Often physical or biological controls are the most efficient means available to the home gardener.

Cultural management:  

A surprisingly simple way to control black vine weevils is to knock them off the plant, collect, and destroy them. This is best accomplished by putting a white cloth at the case of the plant (because the weevil’s protective coloring makes them hard to spot on the bare ground), then gently shaking the plant to dislodge the weevils. Finally, transfer the weevils from the cloth to a jar of soapy water to kill them.

A second technique is to affix cardboard strips covered with a sticky substance to the stems and trunks of susceptible plants in early spring before adult weevils emerge. Trapped weevils can be removed and destroyed.

Good garden sanitation is an effective control, as weevils live in dead plants and ground litter. Cut away the dead foliage of any infested plants to prevent overwintering sites. Discard infested plant material, including the soil around the root system. Weevils also feed on various weeds, so eradicating weeds from the garden will remove an important food source.

Biological management:

Encouraging animal and insect parasites is still another effective control. Animal predators include bluebirds, warblers, and wrens. Insect parasites, such as beneficial nematodes (Steinernema and Heterorhabditis spp.), can be used, but may not give complete control in home landscapes. These can be released into the garden in early June for best results.

Chemical management:

Insecticides are often targeted towards adults to kill them before eggs can be laid. Insecticides for this purpose are sprayed on the plants when adults are present. There are limited insecticide options for treatment of the larvae. Contact the Plant Clinic (630-719-2424 or for current recommendations.

The pesticide information presented in this publication is current with federal and state regulations. The user is responsible for determining that the intended use is consistent with the label of the product being used. The information given here is for educational purposes only. Reference to commercial products or trade names is made with the understanding that no discrimination is intended and no endorsement made by The Morton Arboretum.

For more information, contact The Morton Arboretum Plant Clinic (630-719-2424 or