Weeping weevils are particularly common pests on ornamental plants such as rhododendrons and hydrangeas. We'll show you how to fight weevils naturally.
The voracious vine weevil and its larvae attack many of our plants in the garden and can even kill them. We will show you here how you can prevent this and what you can do against the weevils.
Weeping weevil: Characteristics and way of life
The vine weevil (Otiorhynchus), also called vine weevil, form a genus from the Weevil family (Curculionidae). The ridged vine weevil (Otiorhynchus sulcatus) is also known as the white weevil and is one of the most common species in Central Europe.
The adult vine weevils are dark brown to black in color and usually have light brown markings. Vine weevils cannot fly. The back is often fluted or provided with bulges. The beetles reach a size of three to twelve millimeters and have a strong proboscis, to which they owe their name.
The vine weevil is nocturnal, which is why they are well hidden during the day and only become active at dusk. Most species feed on various herbaceous and woody plants. The beetles can be observed at dusk or at night between April and October. But how do weevils get into the garden? This often happens through the introduction of eggs or larvae in the plant substrate of potted plants.
The life cycle of the vine weevil is partially species specific. The females lay eggs in the ground in summer. In autumn, the unfertilized eggs of the vine weevil hatch into larvae that feed on roots and tubers. The larvae overwinter in the soil and pupate in spring. In early summer, the mature vine weevils emerge, which can live up to three years.
Recognizing vine weevil: damage and symptoms
Before the adult beetles lay their eggs, findbetween May and September the so-called "ripe feeding" takes place. The resulting increased feeding bays on the leaves indicate imminent oviposition and thus also a timely emergence of the larvae - action must therefore be taken.
The harmful appearance of vine weevils is particularly common on:
- Rhododendron (Rhododendron),
- Hydrangeas (Hydrangea),
- Geraniums (Pelargonium),
- Roses (Pink),
- Yews (Taxus),
- Ivy (Hedera helix),
- medlars (Mespilus germanica),
- Cherry Laurel (Prunus laurocerasus),
- Grapevines (Vitis),
- Heath (Erica, Calluna),
- Tree of Life (Thuja),
- Chrysanthemums (Chrysanthemum),
- Fuchsias (Fuchsia),
- Primroses (Primula),
- Cyclamen (Cyclamen) as well as various perennials, berry bushes and wild herbs.
But the often much greater damage is hidden underground and is caused by the vine weevil larvae. The larvae hatch in autumn from microscopic, almost transparent eggs. The vine weevil larvae can reach a length of up to ten millimeters and can be recognized by their brown head and white body. But distinguishing it from other larvae is difficult. First the young larvae eat the root hairs, later even woody parts of the roots can be attacked. With cyclamen, the entire tuber can be hollowed out. Symptoms of an infestation of plants by vine weevil larvae are drooping leaves or a lack of nutrients in autumn despite sufficient water and nutrient supply. This is because the plant no longer has enough roots available. In addition, the damage caused by feeding is an entry point for soil-borne pathogens, which can also damage the plants.
Fighting weevils
If the vine weevil has spread through your garden, there are several ways you can combat it. However, the number of pesticides used to control vine weevil is small.
Biological control of vine weevil
Collecting leaves and shoots from adults is a biological control option. Since the vine weevil is only active at night, this is best done in the late evening with a flashlight. The weevils let themselvesfall with the slightest movement of the leaves. Therefore, it is best to place a tarpaulin under the plant so that you can catch the fallen beetles. You can take advantage of this property by shaking the affected plant. A much less expensive way of combating it is to use a biological agent.
Neem tree oil offers a herbal way to combat vine weevil. The active ingredient in neem oil is absorbed by the plant and thus offers the opportunity to catch the hidden beetles. Our Plantura organic pest-free neem is based on this purely plant-based active ingredient. Organic pest-free neem offers quick protection from being eaten, as the beetles absorb the active ingredient when they eat the plant and lose their appetite. In addition, organic pest-free neem is not dangerous to bees and can be used against various biting, leaf-mining and sucking insects. To use, simply mix organic pest-free neem with water and apply the emulsion to the affected plant. The correct mixing ratio can be found on the product packaging. Please use our organic pest-free neem exactly according to the instructions for use and read the package insert before use.
Chemical control of vine weevil
Weeping weevils are well hidden during the day and therefore difficult to control with contact insecticides. In order to protect beneficial insects in your garden and to protect you as the user, we recommend that you refrain from using synthetic insecticides.
Approved synthetic plant protection products against the vine weevil contain the active ingredients acetamiprid and active ingredients from the pyrethrin group, which are usually used in combination with Abamectin can be used. Although pyrethrins can be obtained from plants, they are toxic to most insects and therefore also damage beneficial insects. Acetamiprid belongs to the neonicotinoids and is considered dangerous to bees.
Fighting vine weevil with home remedies
Home remedies against vine weevil are available as a preventive measure and for mild infestations.
Rainfarntee against vine weevil
For the tansy tea you need about two handfuls of flowering tansy plants (Tanacetum vulgare) or 30 grams of dried tansy herb, which you brew with a liter of boiling water. Simply let the tansy tea cool down and spray the tea undiluted onto the affected plants. The optimal time for application is between May and June.
Vermouth manure againstVine Weevil
To make wormwood manure, you need 300 grams of fresh or 30 grams of dried wormwood (Artemisia absinthium), which you ferment in ten liters of water. If the wormwood liquid no longer foams after about two weeks, this is a sign that it has finished fermenting. You can use the manure undiluted to keep the vine weevil away from your beds.
Garlic or coffee grounds against vine weevil
Garlic (Allium sativum) or coffee grounds have a deterrent effect on the vine weevil and are easy to use. To do this, cut a clove of garlic into small pieces and mix them into the soil. You can also easily work the coffee grounds into the soil. It is best to repeat this method once a month.
Fighting vine weevil with nematodes
Another possibility for biological control is the use of nematodes (Nematoda) against the vine weevil. These allow you to fight the vine weevil larvae. The microscopic roundworms actively move in the soil water to the vine weevil larvae and penetrate them. They transmit bacteria that eventually kill the vine weevil larvae. Our Plantura HB nematodes of the species Heterorhabditis bacteriophora can also be used successfully against vine weevil.
To use, stir the nematodes in water as soon as possible after receipt according to the package insert and pour it over the affected areas. After application, the beneficial insects infest the vine weevil larvae in the soil and kill them. Nematodes are used against vine weevil between April and May or alternatively between August and September. You can find out how to use nematodes as beneficial insects in our special article.
Summary Fight against vine weevil:
- Collect adult vine weevils at night
- Organic agents based on neem oil, such as our Plantura vermin-free neem
- Home remedies such as tansy tea, wormwood manure and garlic
- Nematodes like our Plantura HB nematodes to control the larvae
Prevention of weevils
A first preventive measure is to avoid feeding vine weevil eggs and larvaebring in purchased potted plants. We therefore recommend that you examine new plants for the small larvae in the root ball and complain about the plant if it is infested. Regularly checking the root ball for vine weevil larvae, for example by repotting, is also a preventative option. When choosing the plant substrate, we recommend that you pay attention to a peat-free soil, as vine weevils apparently prefer peat substrates. Our Plantura organic universal soil, for example, is peat-free and provides your plants with nutrients for a long time.
You can prevent mass reproduction and spread to other plants by promoting beneficial insects. Natural predators of the vine weevil include hedgehogs, moles, common toads and birds, lizards, but also many ground beetles and even earwigs. A natural garden design with an undisturbed corner and an accumulation of brushwood and pieces of bark helps hedgehogs to feel comfortable. Bird nesting sites provide a great way to welcome the beneficial birds into the garden.
Weeper Trap
Since vine weevils are nocturnal and hide during the day, you can use this to catch adult vine weevils. To do this, simply take a flower pot and fill it with wood wool, for example. Then place this flower pot upside down on the ground, preferably near the heavily infested plants. Try to set the pot up at an angle so that the beetles can climb in unhindered and hide there during the day. Check the pots regularly and remove the trapped bugs.
If you don't have a flower pot left, you can also use pieces of wood that you put out in the garden. The vine weevils will also hide under the pieces of wood where you can then collect them. Pieces of wood that have some grooves are particularly suitable for this. The beetles can hide well in there.
The larvae of fungus gnats also eat roots. This can cause symptoms similar to those of an infestation by vine weevil larvae. We'll show you how to fight fungus gnats.