It is that time of year again when farmers are going in, and amateur and professional gardeners alike are having to brush up on pests. One of these pests is the Black Vine Weevil (otiorhynchus sulcatus), which is from the Curculionidae family.
Critters, insects, and various enemies will go to work to ensure your garden does not produce healthy, beautiful produce.
Repelling them, in natural fashions that won’t harm the land or crops is covered in this article. If there are signs of garden weevils, going on the offensive immediately is called for to protect it from damage.
Additionally, remember other plants can be impacted, so getting infestations under control is necessary.
By controlling them with natural options, you’ll ensure that your produce doesn’t contain harmful chemicals when harvested, and you do no additional damage to the earth or surrounding plants.
What follows are the various natural and organic ways to get rid of vine weevils and their larvae.
1. Remove Mulch
As black vine weevils prefer heavily moist soil, removal of mulch and other compost items may be necessary.
This should only be done when an infestation is detected, as mulching is a critical component of keeping moisture to plants requiring it in many cases.
The procedure should be done carefully to expose areas they hide, while diligently watching to ensure plants are kept adequately hydrated.
2. Diatomaceous Earth
This treatment, composed of fossilized remains comes in a powder-like consistency.
Diatomaceous earth is a mild abrasive containing 0.1% crystalline silica. It absorbs the waxy cuticle of weevils, ants, and other insects — killing them within 48 hours of application.
Overall, DE is a good natural product to manage hard-bodied insects in and out of your garden and house.
3. Natural Predators
Invite in natural predators, or at the very least, don’t kick them out. Frogs, birds, toads, shrews all feed on these insects.
Allowing them to remain in your garden or even introducing some of these can help to control the population.
Additionally, certain insects such as the ground beetle and rove beetles don’t feed on plants but rather other pests.
Thorough knowledge of all the insects residing on your property should be done to ensure you kill the bad and save the ones that will work for you.
4. Pick Them Off
The most time-consuming, but the easiest home remedy is to pick them off.
Knock off these critters by putting cardboard, umbrellas, or newspaper at the base, shaking the plant to release the weevils. Put them in a sealable bag for disposal.
Stay alert to picking any off by hand that you see, and removing the larvae from the dirt. Remember, for inside or greenhouse planting environments, you will not be immune to this pest.
Checking under plants, in soil, and even benches and the like that present a cool location for them to rest during the day can reveal them.
5. Repellent Plants
Planting certain repellent plants in your garden can help deter insects.
Plants vine weevil dislike include onion, mint, bay leaves, and catnip. Mix in these among your crops to control or prevent infestations.
6. Sticky Traps
A sticky barrier is an excellent trap that can be placed at the base of plants. It traps adults, allowing them to be disposed of away from the garden.
Of course, with black vine weevils, this will only take out the adult form of the insect, and the larvae should be stopped in another manner.
Additionally, if they become laden down with insects in a short time, you might need to employ another eradication method as you are in the middle of a significant infestation.
Remember, there is a wide array of options with barriers. You can buy online or even make your own by using various items like Vaseline or a non-drying glue you are sure to have laying around.
Sticky barriers do need regular inspection to ensure that heavy rains, hot temperatures, and other outliers have not damaged it.
Additionally, getting the barrier replaced when full, ensures it can continue to gather them efficiently.
7. Beneficial Nematodes
You can purchase beneficial nematodes to control the larvae.
These microscopic organisms, which are non-segmented roundworms that can be found in the ground around the globe, help control weevil larvae through infesting it.
They continue to eat on the pest from the inside until their bacteria overcomes and kills the larvae.
They can then infect new hosts, and this process goes on until your garden is free of this pest. Death of larvae starts within 24 to 48 hours of application.
8. Limit Excess Watering
The moisture in the soil feeding your garden is one of the most critical components of a good season. Excessive moisture will help in facilitating vine weevil and other pest larvae, while not enough can, of course, damage crops.
During excessive raining, you should limit additional water to the garden. Also, removal of mulches and such that would trap moisture to a higher than the needed level in the soils should occur.
This balance between enough water to grow your garden, and not so much that larvae find a right home is the most effective method of limiting pests gardeners can employ.
Safe Commercial Black Vine Weevil Insecticides
If you’re wondering how to annihilate these critters organically without having to whip up some homemade concoction, there are safe commercial options available. All these products are OMRI listed or WSDA certified for use in organic farming.
This product is made of Beauveria bassiana, an entomopathogenic fungus that is a natural weevil killer and all-round insecticide. It is a naturally occurring fungus that infests through applying to a pest’s exterior.
It causes white muscadine disease that softens the shell of pests. The fungus thrives off the nutrients in pest bodies, eventually killing them.
The fungus just needs to come in contact with the insect to go to work. Beauveria bassiana is also safe for ingestion in other animals and humans.
BalEnce can be applied throughout the growing season up until harvest. Then a good wash, and you are ready to consume your fantastic harvest.
The main ingredient in this product, Azadirachtin, is derived from the neem tree.
AzaGuard is a heavy-lifting botanical insecticide and nematicide combination that claims to control over 300 insect species.
Insects hate the taste and smell of neem, causing them to try and get away.
Additionally, it is a molting and growth disruptor. It impedes Ecdysone production, which is necessary to move the grubs to full adult stages.
This product is not harmful to humans or other animals that may come in contact with it during application to gardens.
This version of beauveria bassiana fungi is a liquid formula that is applied to your garden.
You will be able to tell in adult pests that it is working as their body color changes to a pink or brown, or may even present with fungus in the body cavity.
Additionally, Mycotrol is useful in all stages of the life cycle of the pest to help control before new adults mature to above-ground status, chewing on your plants.
12. BioCeres WP
This is another multi-functional derivative of the beauveria bassiana fungus that is spread out as a powdery substance or mixed to liquid form and applied.
The spores of this product will adhere to the outer shell of the garden weevil and produce the whitish appearance of the typical steel grey pest.
Infiltration of the outer shell, as the fungi reproduce internally will kill the pest in 7 to 14 days.
BioCeres WP can be used on all types of weevils including the root, rice, and black vine weevil grubs.
Vine Weevil Life Cycle
The lifecycle is one generation per growing season. They will overwinter as nearly mature larvae and come out in the spring.
Hatching occurs in about ten days, and the larvae burrow and start an eating infestation in gardens.
Getting rid of them, and how quickly you act will determine the ability to stop infestation early.
Black Vine Weevil Damage
The signs of an infestation are pretty easy to spot.
There will be notches chewed into plants and white or light brown eggs in the dirt around the base of plants.
Signs of damage to roots will start with eggs visible around the base but can also include wilting and dying plants.
These small insects are slate grey and measure less than an inch, averaging ¾ of an inch. They cannot fly, and spend the night chewing on a large variety of plants.
The small, approximately ½ inch, white, c-shaped grubs of the black vine weevil tunnel through roots in their feeding frenzy and can cause large scale damage and wilt to your plants.
These slate grey, unassuming black pests are a sign of big trouble ahead in your garden. At the very first signs of trouble, start with an infestation control plan, which can be one or many of the items or suggestions listed above.
Remember, the insects you see on the plants are not the worst of it. The larvae still in the moist soil will be doing the most damage when this insect is present.
There are a host of natural options you can employ, researching the best one for your needs is critical.
Based on additional crops in the garden and ornamental vegetation, a broad-spectrum insecticide should work to keep everything healthy and flourishing.
With some due diligence, quick action, and monitoring, you can minimize the risk to your garden!