How to Get Rid of Black Vine Weevils

It is well known that the boll weevil (Anthonomus grandis) caused a great deal of destruction in cotton plants throughout the United States at the beginning of the 1900s. However, disregarding the black vine weevil would be ill-advised. It’s a smart move for gardeners to focus more on the black vine weevil from Europe (Otiorhynchus sulcatus) than the more famous member of its species. This particular species of weevil feeds off of various flora commonly used in landscaping, causing not life-threatening but aesthetically displeasing destruction. The larvae’s assaults take place at the root, and in certain scenarios, it may cause irreparable destruction. The pest can be seen across a wide area of southern Canada and northern America.

Identify what a black vine weevil looks like, what plants are vulnerable to this pest, and methods for managing them.

What Do Black Vine Weevils Look Like?

This insect is a dull black or gray in hue and measures 3/8 of an inch in length. It is known as the black vine weevil. This creature has a body resembling a pear which is marked with indentations, as well as six appendages for traveling. Two antennas are extending out a great distance from the head, and the beak is also distinguished. The black vine weevil does not have the ability to take flight; instead, it travels by foot.

The grubs that hatch from these insects are comparable to the grubs you would see from beetles like the June bug (Phyllophaga longispina) and the Japanese beetle (Popillia japonica). The larvae resemble worms due to their lack of legs and a length of about 1/2 inch. Their bodies are shaped like a C, being white in the main with reddish-brown heads.

Signs of a Black Vine Weevil Infestation

The activity of adult black vine weevils typically occurs between mid-spring and late summer. The caterpillars they produce remain active from mid-summer all the way through to the following spring. Black vine weevils, which are fully grown, feed on the foliage of plants during the evening hours. As a result of their feeding, they leave crescent-shaped depressions along the edges of the leaves. The plant’s look is affected by this harm, yet it is improbable that severe wellbeing issues will arise as a result.

The immature stages of the organism feed on the roots of plants and can encircle their lower stems. The destruction caused can interrupt the flow of needed water and nutrients to the plants’ above-ground portions. The harm they cause is more consequential than that inflicted by the grownups. The harm they cause will cause the plant to become limp and discolored; it can even lead to the plant’s demise. The species is also referred to as “root weevil” due to its damaging behavior during the larval stage.

From May through June, examine known host plants for any harm inflicted by adult black vine weevils. Grapevines, generally referred to as Vitis spp., commonly have problems with certain pests; thus the “vine” in the name of the bug.

You may question why we do not use the visible destruction of plants due to the larvae as a sign of a black vine weevil infection since they, too, cause damage. Two factors contribute to why grubs can cause so much damage without being seen: they live and feed beneath the soil, meaning their presence is not obvious; and once their eating starts to show up on plants, the harm they’ve done is often too extensive to be remedied in the same season.

Look closely at plants in the future, and if you spot the grown-up insects that have come up from larvae, do something right away to get rid of them so they don’t produce any eggs. Carrying out this action will inhibit the advent of a new set of people and protect next season’s garden.

What Causes a Black Vine Weevil Infestation?

Since black vine weevils are unable to fly, the area they can cover by themselves is limited. However, they can use human activity to move around in secret for a long distance. The potted plant that you acquire from a garden center may be a hidden source of danger, as it may contain larvae in the soil around the roots. Once the larval stage is complete, they are capable of moving to other vegetation on your property.

Purchase your potted plants from trustworthy nurseries only. Investing more money in a reliable nursery is beneficial, as these companies take extra precautions to stop black vine weevil infestations in the soil. Examine the base of the plant you recently obtained (or plan to transfer to planted in the ground) for grubs and exterminate any that are found.

Controlling Black Vine Weevil What Can You Do?

There are many ways to get rid of adult insect pests.

It is okay to cautiously apply insecticide to the leaves of plants in the months of May and June.

Here’s one technique that works well for timing your application correctly:

In the beginning of May, lay out 6-inch by 6-inch wooden blocks onto the mulch near the plants that could be exposed to the parasitic insects.

Burlap can also be used for this purpose. When the temperature rises, raise the burlap cloth or flip the boards.

If you notice any adult black vine beetles scurrying around underneath, this is an indicator that you have a problem.

You can start collecting the grown-ups and putting them in a container of sudsy hot water whenever you spot them. It is inevitable that this will not eradicate all of them.

It will typically take a period of two to three weeks after the initial sighting for the females to lay eggs.

Make your first pesticide application at this time.

It would be beneficial to apply your remedy at twilight in order to have the most successful impact on evening-feeding insects while simultaneously causing the least amount of disruption to helpful bugs (notably bees).

Apply a registered pesticide as a soil drench during the period from July to October to eliminate the larvae.

In the past, the optimum practice to achieve this goal was to irrigate the ground or submerge young plants with the potting material intact in a mixture of the organophosphate pesticide named Dursban (chlorpyrifos).

This pesticide poses a serious threat to humans, animals, and vegetation as it can damage the roots of the plants it is meant to protect.

Nowadays, Talstar (bifenthrin) is the recommended pyrethroid for controlling both baby and adult insect infestations.

Pyrethroids are desirable for pest control because they decompose quickly in the environment, which makes them an ideal choice for both residential and farm use.

Bear in mind that the quick deterioration of this chemical is mainly brought about by exposure to sunlight.

If applied to the soil, pyrethroids have an extended period of persistence.

Additionally, if diluted, certain larvae of the black vine weevil may persist following soil saturation with bifenthrin and will eventually generate an immunity to it which will be inherited by their progeny.

The black vine weevil larvae may stay in the same spot if they have found a good supply of food, which can make using a drench not very effective.

This behavior would limit their contact with the pesticide. Nematodes are more suitable than pesticide soil drench for getting rid of larvae, among many other benefits.

A comprehensive approach to controlling black vine weevil would involve an Integrated Pest Management Plan (IPM).

Weevils and grubs are widespread worldwide in outdoor areas such as gardens, yards, and fields. The black vine weevil is one of the most frequently encountered types.

You are unlikely to ever be fully rid of them, but a good Integrated Pest Management (IPM) plan includes careful use of:

• Pesticides
• Natural alternatives
• Beneficial insects and other organisms

It can be a big help in preventing these pesky creatures from becoming a problem.

It is imperative that you take action against both weevils and larvae; thus, it is essential to apply topical pesticide treatments to the leaves of plants, as well as soil drenches and nematodes in conjunction.

To get the optimum result, use leaf treatments once a month during the springtime and summer season to keep adult females from reaching sexual maturity and starting to lay eggs.

Remember that if you use the same foliar product over and over, the weevils will develop an immunity to it, so switch to a different one every now and then.

It is recommended to apply pyrethroid-based products on a monthly basis, particularly if there is a serious infestation present. Use neem oil based insecticide products in between times.

In addition to the use of pesticides and natural solutions, add these four techniques to your arsenal:

Eliminate any grubs or beetles that are visible through manual extraction. Have a pail of sudsy water close by when working in the garden. This is a great container for all types of pests.

Structural impediments and hindrances can aid in regulating the travel of pests. The stems and trunks of plants and trees can be protected from adult BVW by making a barrier of materials that are impassable, such as plastic with a grease coating.

It is advisable to trim plants regularly to avoid the branches of one plant touching those of another. This prevents the bugs from climbing from plant-to-plant.

In order to impede the actions of baby and older pests, bury aluminum flashing around the plants a couple of inches above the ground and down at least 5 to 6 inches underneath the soil.

Spread a layer of auto mechanic’s (lithium) grease over the area of the metal that sticks out. This grease will remain in position even in light rainfall. You should periodically give it a renewal, particularly when it has rained very hard.

If you notice any bugs, such as weevils or grubs around the plant, make sure to scoop up the soil and get rid of them before creating your bug barricade. This way, you won’t be trapping them in when adding your bug protection.

Predatory Insects

Bring in predators like Assassin bugs, types of praying mantis, and Carabidae beetles to get rid of Black Vine Weevil and other bugs.

Keep in mind that it is essential to safeguard your helpful bugs because they will benefit you by consuming both immature and grown up forms.

Insects that feed on other creatures may be less tolerant to pesticides than Black Vine Weevils, which have a tendency to develop immunity quickly.

Maintaining a low use of pesticide and having a comprehensive and wide-ranging Integrated Pest Management (IPM) system in place is a good justification.

In a yew nursery where insecticide use was frequent, a survey of the ratio of Black Vine Weevils to predatory insects utilizing pitfall traps found that there were only 200 predatory insects and 1500 Black Vine Weevils.

In comparison, an inquiry done in a nursery which did not utilize pesticides provided 950 predatory insects while only 3 Black Vine Weevil were detected.

In order to try this out yourself, bury a 16-ounce plastic cup in the soil in your garden until it is even with the edge of the cup.

Put it in a spot where Black vine weevil could be encountered. A rhododendron bush serves as an ideal location.

Apply a layer of motor oil around the rim of the cup (approximately 1 inch) to prevent bugs from escaping.

Check your trap every few days. You will have an understanding of the balance between prey and predator in the area where you find black vine weevil and predatory insects.

How to Prevent a Black Vine Weevil Infestation

In the event that larvae of the black vine weevil make it onto your land, it is possible to prevent or delay the adults from emerging.

The best approach is to remove the plants that insects depend on for sustenance. Plants commonly attacked by black vine weevils include the following:

• Hosta (Hosta spp.)
• Euonymus (Euonymus spp.)
• Hemlock (Tsuga canadensis)
• Mountain laurel (Kalmia latifolia)
• Azalea (Rhododendron spp.)
• Yew (Taxus spp.)

If you find yourself drawn to one or more of the identified host plants and choose to bravely cultivate them in your yard, there is still a way to reduce the amount of destruction that could come from black vine weevils. This approach capitalizes on the inability of black vine weevils to fly. Trim the branches of a host bush (such as mountain laurel) that is planted in a cluster or grouping with other plants, in order to make gaps between the vegetation. By taking this action, it eliminates the pathways that black vine weevils use to go from one plant to another. Similarly, you should trim off any branches that arch down towards the ground of the host plants you know of in order to prevent the black vine weevils from gaining access to your plant.

FAQ

Can a black vine weevil bite you?

Although this insect appears to be quite intimidating with its strong snout, it does not harm humans with a bite or sting.

Is the black vine weevil just an outdoor pest or does it also enter the home?

Sometimes a black vine weevil will inadvertently be brought into the house with a potted plant when it is brought indoors. Once inside, Begonia and other common houseplants can be harmed.

Outside of the plant damage it causes, is the black vine weevil harmful in any other way?

This insect poses no threat to animals or any damage to buildings.