Black Vine Weevil Control: How to Get Rid of Black Vine Weevils

This page is a general DIY guide for black vine weevil control. Using the products and methods suggested, you will get control of black vine weevils. Follow this guide and the recommended products to control black vine weevil infestations completely.

Black vine weevils, Otiorhynchus sulcatus, also known as the Taxus weevil, are a widespread pest of 100 or more types of field and container-grown ornamental plants, trees, shrubs, crops, and small fruit crops across the northern half of the United States. This common root weevil pest is most commonly seen in its larvae stage on yew, hemlock, rhododendron, asters, cyclamens, impatiens, and several other broad-leaf evergreens.

Even though black vine weevils are nocturnal and flightless, they are the most encountered root weevil pests. One reason for this could be that black vine weevils are parthenogenic females, meaning they reproduce asexually without the aid of a male. Other probable conditions might be that homeowners purchased an infested container-grown plant with black vine weevils hiding in the first layer of soil. Once these pests invade your property, they can be found at least 10 inches beneath the soil.

There is one generation of black vine weevils per year, but depending on the season, there could be both adult and larvae stage activity. Both the adult and larvae stages of these pests pose a set of ongoing cosmetic to root damages, leading to the eventual death of foliage. For this reason, refer to the steps and products listed in this DIY guide to prevent and eliminate each stage of black vine weevil emerging on your property.

Identification

Before proceeding with a treatment program, you must be certain you are dealing with a black vine weevil infestation. Careless identification can lead you to use the wrong treatment products, wasting your time and money. Below are some characteristics of black vine weevils to aid in identification:

• Adult black vine weevils are tiny insects that grow up to 1/2 long.
• These insects have pear-shaped bodies that appear black in body color, but you can see several gold dots on their wings.
• Larvae have soft, white bodies that grow up to half an inch in length. They have orange or brown head capsules, usually curled into a C-shape. Mature larvae, pupae, are white with prominent legs and a pair of antennae.
• Black vine weevils have wings but cannot fly as they crawl from place to place with their six legs.
• Like all weevils, the black vine has a long snout-like mouthpart to help it burrow and feed. They will also possess a pair of bent antennae.

Use the description and image above to determine whether the pest you face is a black vine weevil. If unsure, you may email us with a photo of your pest or in person at one of our store locations for further pest control assistance and advice.

Inspection

Once you have confirmed the infestation is black vine weevils, you can move on with the inspection. During this phase, you will locate the areas where black vine weevils are infesting and observe the conditions allowing them to thrive. This information will help determine where to apply pesticide products without wasting product material.

Where to Inspect

Black vine weevils are attracted to areas containing significant amounts of moisture. These pests will invade the root system and leaves of various trees, shrubs, crops, small fruit crops like strawberries, container-grown plants, potted plants, and other types of plants. The most common place to find the black vine weevil is in your trees, like hemlock or broad-leaved plants like rhododendrons or yews.

When the weather has been consistently hot and dry, these pests can invade homes' interiors through cracks and crevices around plumbing and the foundation. A home's interior is not at risk from black vine weevil activity unless there are indoor potted plants available for the pest to feed on. If you do not possess any indoor potted plants, then this may suggest a moisture issue.

What to Look For

Throughout its life cycle, the black vine weevil will inhibit beneath the soil of high-moisture areas such as gardens, crops, or tilled areas. In its adult stage, the black vine weevil becomes a nocturnal pest that buries itself up to 10 inches in the soil.

From May to late June, larvae can be found in the soil underneath or near plants. You can dig 4 inches beneath the turf with a trough to see if there are c-shaped white grubs. Watering the soil and plants is recommended to draw black vine weevil larvae closer to the surface. If you witness one pest during your digging, this could be a sign of a more significant infestation, as black vine weevils are known to bury deep into the soil. Other signs of larvae activity can be seen on the plant's roots and crown. Feeding damage done by the larvae may cause discoloration, such as yellowing, wilting, stunted plant growth, branch dieback, and loss of leaves.

In late spring, around the end of May to June, black vine weevils emerge from the soil as adults. Damages from adult black vine weevils can be seen with a chewed crescent to circular-shaped notches on the plant leaves. You may inspect your property at night to identify this nocturnal pest emerging from the soil to feed. Once you flash a light on the black vine weevil or disturb them in any other way, they will pretend to be dead and fall to the ground.

About four weeks after emerging, the adult black vine weevil can lay up to 500 eggs around the base of plants. This activity typically occurs from late July to September. Black vine beetle eggs have a smooth and shiny white appearance. Over time, this white coloration fades to brown.

Treatment

Before proceeding with treatment, you will need to wear the appropriate personal protective equipment (PPE) to protect your hands, face, eyes, mouth, and skin when handling or applying any pesticide materials.

Black vine weevils are resistant to most pesticide materials except those containing the active ingredient permethrin, imidacloprid, or bifenthrin. To protect your foliage, we recommend using a combination of systemic and contact products to eliminate as many black vine weevils as possible and ensure total control.

Step 1: Drench Dominion 2L

Dominion 2L is a liquid insecticide containing the active ingredient imidacloprid 21.4%. It is labeled to treat pests such as black vine weevil larvae around trees and shrubs. As a systemic formulation, this product will safely eliminate the larvae without harming trees and shrubs as long as the instructions on the product label are followed.

Determine how much Dominion 2L to use by calculating the square footage of the treatment area. To find this, measure the length and width of the treatment area in feet and multiply (length X width = square footage).

To target black vine weevils in trees, you will need to apply a drench application around the base of the trees at the rate of 0.1 to 0.4 oz. of Dominion 2L per 10 gallons of water per 1,000 sq. ft.

To get rid of black vine weevils in shrubs as a drench application, use 0.1 to 0.2 oz. of product per 10 gallons of water per 1,000 sq. ft.

Directly apply the solution to the plant's root area, then allow the treatment to fully dry.

Fill your hose-end sprayer with the appropriate amount of Dominion 2L, but do not add water. Attach the filled hose-end sprayer to the end of your garden hose until secured. Spray the required amount of water to evenly mix the solution. Once this solution is mixed, you will spray the root zone until wet, but not to the point of runoff.

Step 2: Broadcast Supreme IT

Supreme IT is a broad-spectrum liquid insecticide that eliminates over types of pests, including adult black vine weevils. Once applied, the product's active ingredient, bifenthrin 7.9%, works to paralyze the black vine weevil, leading to death. This product also provides a long-lasting barrier treatment, keeping pests such as black vine weevils away from treated areas for up to 90 days.

Calculate the square footage of your treatment area to determine how much product to use. Measure the treatment area's length and width in feet, then multiply together (length X width = square footage).

With a hose-end sprayer, broadcast this product across your lawn at the rate of 0.25 to 0.5 oz. of Supreme IT per gallon of water per 1,000 sq. ft.

Pour the measured amount of Supreme IT into the hose-end sprayer tank, but wait to add water. Attach the filled hose-end sprayer tank to the end of your garden hose. Once attached, spray the appropriate amount of water until the solution is well-mixed. Apply the product over ornamental shrubbery on your property, making sure to treat the foliage and the undersides of the leaves. Spray until wet, and allow the foliage to dry completely.

Retreat your property when 90 days have passed from the first application to eliminate adult black vine weevil activity.

Do not apply this product to crops.

Prevention

Once you have successfully eliminated black vine weevils from your property, you will want to ensure these pests do not return. Refer to the following preventative measures to keep black vine weevils away from your lawn.

• Prune overgrown tree branches, leaves, and limbs to avoid shade and moisture from overhanging branch. This will also encourage new plant growth.
• Adjust the levels of moisture in your yard by watering with no more than an inch of irrigation once a week in the early morning. Watering in the early morning will help give the foliage enough time to soak in the moisture before black vine weevil emerge in the night to feed.
• Improve drainage in yard by directing rain gutters away from plant bed areas and foundation of home. Repair leaks and other moistures in the interior of home to deter black vine weevils from coming inside during hot or dry conditions.
• Remove or cover container grown plants with appropriate plastic sheeting during the night.
• Take note of areas with past black vine weevil activity and rearrange plant beds to avoid overwintering pests and larvae.
• Regularly mow your turf when it has reached a height of 3 or 4 inches to disturb egg sites and potential black vine weevil activity. This will also help to encourage water evaporation during the day.
• Seal crack and crevices around home with caulk to prevent black vine weevils from traveling inside.
• Finally, keep up with regular scheduled applications of your residual insecticides. Dominion 2L and Supreme IT both provide control for 3 months, and should be applied on a quarterly basis for year-round control.

Key Takeaways

What are Black Vine Weevils?

• Black vine weevils are a common landscape, crop, tree, shrub, and ornamental foliage pests that feed in both their adult and larvae form causing significant damages to plants.

How to Get Rid of Black Vine Weevils

• We recommend making an application of Dominion 2L around your trees and shrubs for larvae activity and Supreme IT across your lawn to eliminate and prevent adult black vine weevils.

Preventing Black Vine Weevil Reinfestation

• To prevent black vine weevil infestations, we recommend making continual applications of Supreme IT and Dominion 2L on a quarterly basis. As a moisture dependent pests it would be best to adjust watering practices, raking and trimming leaf branches and other fallen foliage, and repairing any moisture issues within home.