The black weevil is a feared garden pest that likes to attack the leaves and shoots of plants with robust foliage and develops a considerable appetite in the process. However, it is not this feeding damage that massively weakens the laurel cherry. The larvae of the beetle, which attack the roots, damage the plant so badly that it can even die.
How do I fight black weevils on cherry laurel?
In order to successfully combat the cherry laurel weevil, you should lure beetles into wood wool traps, check them daily and destroy them. However, it is more effective to control the larvae using nematodes, which are applied in spring and late summer.
The Pest
The furrowed black weevil and the large brown weevil are the most common in our gardens. Both species are dark-colored, nocturnal and reach a size of about one centimeter. The beetle prefers areas with humus-rich soils where the white-colored larvae find optimal living conditions. They develop underground and feed on the roots of host plants, to which they can cause considerable damage.
The harmful image
Plants affected by the black weevil show a typical damage pattern that is referred to as bay damage. The leaves are semicircular, but do not show any pitting. The larvae, which live in the soil, initially feed on the fine root hairs of the laurel cherry. From there they eat their way to the main root and gnaw all underground parts of the plant.
Discover the beetle
The black weevil is nocturnal. To detect the beetles, it is recommended to use a flashlight to search the laurel cherry for the pests after dark.
Fighting the voracious beetle
Once you have spotted the little crawlers, you should place containers filled with wood shavings under the laurel cherry. This is where the black weevils will hide during the day, so you can destroy them. Check the traps daily to prevent the pests from multiplying.
It is more effective to fight the larvae. The optimal time for this is April and May as well as August and September, when the larvae have recently hatched in large numbers. Specialist retailers stock parasitic nematodes (€11.00 on Amazon), which kill the offspring of the weevil in a few days without causing any harm to humans or animals. The effect of this environmentally friendly method is very lasting, as the nematodes continue to multiply in the bodies of the dead black weevil larvae.
Nematodes – natural helpers in the fight against the black weevil
You should spread 500,000 nematodes per square meter, which are available commercially in tightly sealed plastic bags with carrier powder. Before releasing the beneficial insects, water the soil thoroughly so that the nematodes have enough moisture to reach the larvae. The animals work most effectively at soil temperatures between 15 and 25 degrees. Since they are sensitive to UV light, we recommend applying them in the evening or when the sky is cloudy.
Tips & Tricks
Neem press cakes ruin the appetite of the voracious beetles. These are worked flat into the soil around the cherry laurel. The neem oil it contains is absorbed by the bushes and is toxic to both the beetles and the larvae of the black weevil.
