Know and fight the pest

the essentials in brief

• Black weevils can be best controlled by collecting them and / or using nematodes
• The pests do not like the smell of neem oil
• Beneficial organisms such as moles, hedgehogs and shrews prefer to eat the insects
• Insects do not like loose, peaty soil

Fight black weevils effectively

Continuity is important for successfully combating the extremely stubborn pest, because the infestation cannot be contained with a one-off measure. The animals multiply too quickly and too numerous for you to catch them all at once.

Collecting

By collecting it by hand, weevil infestation can be combated quite well. However, you can only catch the nocturnal beetles late in the evening or at night, preferably during the summer months between May and August. Take a flashlight with you to catch the animals doing their nocturnal activity - and be as calm as possible. Ultimately, weevils perceive the finest vibrations through their leg hairs and flee when danger is imminent.

Collecting can be made easier if you put Flammende Käthchen (bot. Kalanchoe blossfeldiana), which the vine weevils especially love. Many of the beetles will migrate to this plant and are easier to catch.

Fight biologically with nematodes

If the black weevil infestation is already very pronounced and your plants are plagued by the countless larvae, biological control of the animals with the help of nematodes helps. These are tiny roundworms called Heterorhabditis bacteriophora that you come across from Well-known providers such as Bayer or Neudorff can be bought in specialist gardeners or simply order from Amazon can. Nematodes destroy the vine weevil larvae by penetrating them and leaving bacteria there that are deadly for the beetle maggots. The plant is not damaged in the process.

In order to destroy the larvae in a targeted manner, precise dosing of the nematodes is necessary. Depending on the square meter treated, you should apply around half a million roundworms. Distribute them as soon as possible after receipt, as the tiny ones die off quickly. However, they usually last a few days if you store them in a cool place. Nematodes need moisture to be active. The following video shows how to properly deploy the animals:

It is best to proceed according to this scheme when applying the roundworms:

1. First, water penetrating the soil to be treated.
2. Do the watering early in the morning on a warm summer day.
3. Wait until the evening.
4. Fill the nematodes from the packaging into a watering can filled with water.
5. Stir gently.
6. Use the mixture to water the root area around the plants to be treated.
7. Keep the soil area evenly moist for the following weeks.
8. Avoid waterlogging, however, as neither plants nor nematodes can tolerate it.

Application in the dim evening hours is important because the beneficial animals are very sensitive to UV light. Ideally, the floor should also have a temperature between 15 and 25 ° C so that the nematodes feel comfortable in it.

time

When using nematodes, however, it is not just the way they are used, but above all the timing that is important. Most products are only effective at floor temperatures of 12 degrees Celsius or more, which must be maintained over a period of four hours a day. With this in mind, there are two possible treatment periods in the year during which the nematodes can work particularly successfully:

• April May: in spring you control overwintering larvae, pupae and beetles
• August September: in late summer the nematodes kill larvae in various stages

Infested plants in the apartment, on the other hand, can be treated all year round, as there is no frost here.

Neem press cake / neem oil

Neem oil, which is made from the seeds of the Indian neem or neem tree (bot. Azadirachta indica) is an important pesticide. The natural insecticide contains the substance azadirachtin, which prevents pests from multiplying and thus lets them die. The remedy is also very effective against the black weevil, whereby you can click here for an easier application Neem press cake - these are the residues that are left over from the production of the oil - fall back can.

Work this flat into the soil around the plant, which you should repeat every two months. Calculate a consumption of around 50 grams per square meter of surface. The plants take up the active ingredients from the press cake, so that both the larvae and the adult beetles gradually cease to eat.

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Do not use neem products and nematodes at the same time

Natural enemies

Basically, every garden owner should be happy, the hedgehogs, moles, shrews, common toads or lizards in the garden hat: These animals like the adult weevils and their larvae to eat and thus keep the population small amount. If you create refuges and hiding places for these animals, the voracious beetle has no chance. Free-roaming chickens also like to scratch for the nutritious larvae, but they cannot be used everywhere in the garden. The poultry eats not only the pests, but also all kinds of vegetables and fruit.

This is how you recognize a black weevil infestation in good time

Since the black weevil has a wide range of hosts, it quickly eats its way through the garden and attacks a large number of different plant species. However, it has some preferred food plants and nests mainly in rhododendrons, cherry laurel, Hydrangeas, Roses, berries, yews and Bergenia a. But there are also many other shrubs and trees on his menu.

The damage caused by eating also manifests itself in two ways. The adult beetles feed on the above-ground parts of the plant, while the larvae eat the roots and other underground parts of the infested plant. The beetle damage is quite easy to recognize, because the adult animals eat real bays in the leaf margins. On the other hand, it is much more difficult to identify larvae infestation, because here the damage pattern shows itself to be quite inconsistent. The table clearly shows which symptoms indicate a black weevil infestation:

If you suspect an infestation with black weevil larvae in withered plants, you have to look in the root area. The small, white maggots are often found here in great abundance. It is important to act as quickly as possible if an infestation is identified in order to prevent further damage or even death of the plant.

Check potted plants after winter

Unfortunately, the black weevil not only feels at home in the garden, but also in potted plants - regardless of whether they are in the winter garden, on the balcony or in the room. In most cases, indoor and other potted plants are attacked by potting soil contaminated with eggs and / or larvae. You should therefore carefully check potted plants with the described damage patterns for any beetle larvae or even adult beetles that may be present. Such a control is particularly important when clearing the winter quarters in order to prevent further spread in good time.

Prevention is better than fighting

So that you do not get a problem with the black vine weevil in the first place, you should prevent an infestation. A few measures help here, which make life difficult for the pest and therefore can hardly reproduce:

• Avoid potting soil containing peat for potted plants
• Garden soil often with a hoe or Digging fork work gently (do not damage roots!)
• Careful pricking into the ground with the digging fork is sufficient
• onto Mulching do without, weed weeds more often instead
• Keeping chickens - the larvae of the black weevil like to pick them out
• Water plants regularly with plant strengtheners
• Tansy or wormwood manure are particularly suitable

Make and use tansy or wormwood manure

Tansy and wormwood can be used to easily produce non-toxic, but still effective plant strengtheners that not only drive away the black weevil. Tansy, for example, also helps against aphids, whiteflies and other leaf sap suckers as well as against the wrong things that often occur in the garden mildew. Wormwood, on the other hand, also helps against rust diseases and mites. Both plants can be found in nature, especially the tansy is common in the summer months at the edges of fields and roads and can be easily recognized by the bright yellow button flowers. Collect the flowering herb whole and either use it fresh or dry it as a supply for later use.

Preparation of the plant manure in the step-by-step instructions:

1. Crush one kilogram of plant matter (leaves, flowers, stems)
2. Fill this into a plastic bucket.
3. Do not use a metal container as this can cause undesirable chemical reactions.
4. Pour 10 liters of cold water over the plant material.
5. Add a handful Rock flour(€ 12.33 at Amazon *) added, that binds the smell that develops later during fermentation.
6. Put the bucket in a dark and warm place.
7. Cover it with a breathable net or something similar. a.
8. But don't put a lid on.
9. Let the mass ferment for 10 to 14 days.
10. Stir the liquid manure daily with a wooden stick.

The liquid manure is ready as soon as no more bubbles rise or appear. the liquid no longer foams. Now dilute it 1:10 with water and water the endangered plants with it at regular intervals.

Way of life and reproduction

However, the pests are rarely seen, because black weevils are both nocturnal and fast. The flightless animals are excellent at climbing and perceive even the finest vibrations through special hairs on their front legs. As a result, they quickly recognize approaching dangers, simply drop on the ground and hide. Even during the daytime, the animals spend their time in protective hiding places near the infested plants, preferably in the mulch, in leaves or buried in the upper layer of the earth.

The animals only become active at dusk, when they climb up the plants and feast on the leaves, shoots and buds of herbaceous plants. In contrast to many other insects, adult vine weevils live to a fairly old age and can live up to 12 months.

Development of the larvae

While the adult beetles show their first signs of feeding in spring, the larvae do not become active until late. The eggs are laid in the open quite late between July and October, whereby the females do not have to be fertilized. Instead, the pest usually reproduces through parthenogenesis, i.e. through first generation. The eggs are round, white and very small with a diameter of less than a millimeter placed in packets near the host plants, with each female beetle laying up to 1000 eggs can.

The larvae, which are quite similar but significantly smaller, hatch after about three weeks and spend their entire larval phase underground. How quickly (or slowly) they go through the various stages of their development depends heavily on external conditions. These weather conditions are ideal for rapid pupation and thus even faster reproduction:

• Temperatures between 16 and 27 ° C
• sufficient soil moisture
• no drought

In favorable weather, the larval phase lasts only two months, in unfavorable conditions, however, the pest can remain in this stage for up to 12 months. The maggots overwinter in the field without any problems and become active again in spring. There is only one generation per year, with the exception of greenhouse and winter garden crops: the animals do not take a winter break here due to the favorable temperatures.

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What does the black weevil do in winter?

What are black weevils?

Vine weevil (lat. Otiorhynchus) are a genus of beetles from the family of weevils (lat. Curculionidae), which cause great damage both in agriculture and in hobby gardens. Both the adults, known as adults, and their larvae have great appetites. While the adult beetles live above ground and feed mainly on leaves, young shoots and buds, the are Grubs in the soil and eat roots, rhizomes and tubers there.

species

The black weevil genus is very species-rich and includes around 1000 different species. The furrowed vine weevil (lat. Otiorhynchus sulcatus) as a pest in the garden. The species is not very specialized in certain types of plants. In addition, the following species make life difficult for the gardener:

Due to the great importance of the furrowed vine weevil, the article only deals with this, but there are the different species are very different in terms of their biology and possible control options similar.

Appearance of the black weevil

The furrowed black weevil has a characteristic appearance of beetles, which has the following features:

• legs: three articulated pairs of legs
• Deck wing: armor-like, strongly arched
• coloring: dark to brown, without metallic sheen
• size: up to 12 millimeters long
• Special marks: granular or corrugated back area, often dotted yellow or brown
• Trunk: strong, twice as long as wide, lobe-like enlargements
• Larvae: legless, yellowish-white, brown head capsule
• Larva size: approx. one centimeter, crooked posture is typical

Are there any effective insecticides against the black weevil?

Toxins in the garden not only kill pests, but also destroy beneficial insects and damage biological diversity.

Commercially available chemical sprays such as thiacloprid, imidacloprid, or thiamethoxam are specifically not recommended for garden use as they are not only fight the black weevil - on the contrary, it destroys the delicate biological balance and causes considerable damage to flora and fauna can.

For example, these funds are made responsible for the death of bees - with the result that Fruit trees and other plants that rely on pollination have little or no fruit left wear. For this reason, refrain from using toxic pesticides such as these, because you have enough effective biological preparations on hand against pests such as the black weevil.

frequently asked Questions

Is it true that coffee grounds help against vine weevils?

In fact, dried coffee grounds are both a good fertilizer and an old home remedy for the black weevil. Since the remedy is not very effective in comparison to other preparations, you should not rely on them alone.

Does garlic help against the vine weevil?

Garlic is also one of the plants that the vine weevil does not like. As a result, you can counteract an infestation with garlic broth or stock just as effectively as with a remedy made from tansy or wormwood. The remedy also helps against many other pests (for example against aphids, thrips or spider mites) as well as against various plant diseases. And this is how you make the brew:

1. Crush 3 to 5 large, fresh cloves of garlic into small pieces.
2. Put the garlic in a container.
3. Pour a liter of hot, but no longer boiling, water over it.
4. If the water is hard, add a splash of fruit vinegar.
5. Let the brew steep in a warm and dark place for 24 hours.
6. Sieve off the brew and fill it up to one liter with water.
7. Fill it into a boiled, sealable glass bottle or a similar screw-top jar.
8. Water or spray endangered or infested plants with it.
9. Repeat the application at regular intervals.

How can I build a trap myself?

You make it easier to collect the beetles at night if you build this one trap. For this purpose, place flower pots filled with wood wool or thick, well-moistened cardboard directly under the infested plants. During the day, the pests like to take these as hiding places and can thus be caught in a very targeted manner. Alternatively, rotten, well-soaked boards also help.

Why does the black weevil treatment not help?

If, despite repeated treatments, an infestation with the black weevil occurs again and again, then the supposedly ineffective remedy is usually not to blame. Instead, there could be various reasons why the measures were unsuccessful:

1.) The treatment was not carried out often and / or tightly enough so that some larvae and / or beetles have survived and are now proliferating.

Countermeasure: Repeat the treatment, but this time more closely and over a larger area.

2.) Beetles and / or larvae survived in hiding places not covered by the treatment, perhaps even overwintered, and migrated from there.

Countermeasure: Remove any hiding places (including plant pots, boxes and the like!) And treat them thoroughly.

3.) Adult beetles have migrated into yours from outside, for example from your neighbors' garden.

Countermeasure: Treat your plants again and make your neighbors aware of any black weevil infestation.

Unfortunately, the fact is that, despite the effective means available, the black weevil can keep recurring. The animals are simply too willing to reproduce and are not well adapted to certain plants to be able to kill them off easily. One remaining larva is sufficient, which pupates in the following year and in turn lays 1,000 eggs again - and the big eating is already underway again.