Only when it begins to get dark does the vine weevil come out of its hiding place and eat its fill of leaves, young shoots and buds. However, its larvae cause far greater damage: they target crop and ornamental plants.
Whether rhododendron or cherry laurel, boxwood or roses: a vine weevil prefers plants with thicker leaves, but if there is not enough choice, it will also gnaw at flowers and perennials or even weeds. “The beetle causes typical feeding spots on leaves and needles that protrude from the edge into the leaf surface. This so-called bay damage occurs when the beetle eats into the leaf from the edge of the leaf,” explains the Lower Saxony Chamber of Agriculture, which is typical of signs of an infestation. Because vine weevils are nocturnal and extremely shy, they are difficult to control during the day. In addition, their larvae are far more dangerous to crops and ornamental plants.
This is how you recognize an infestation in good time
In addition to the feeding damage described above, which speaks for an infestation, you can recognize the shy beetles by the following characteristics at the latest when it gets dark (and certainly at night): They are only a few millimeters in size, usually brown or black in color and often have small yellow dots on their ribbed armor. They owe their name to the strong proboscis on which the antennae are located. The insects mate between spring and autumn – each female is then able to lay up to 1000 eggs. Preferably near the roots so that their larvae have something to eat within a few weeks of hatching. And thus cause great damage to the roots.
How to fight vine weevil
Unlike other beetles, vine weevils cannot fly. If they are threatened by danger or if they are disturbed while eating, the animals simply drop – for this reason you have to be quick if you want to catch the insects. It is best to use a flashlight and collect the beetles (when it is dark outside) from the infested plants. If you want to save yourself the work, you can use another trick: put wood shavings in an empty flower pot and place them under the infested plant. During the day, vine weevils hide in it or, if threatened, drop on it.
How to deal with larvae
The larvae of the vine weevil, which are in the ground near the roots, are much more difficult to control. So-called nematodes have proven to be particularly helpful here: These are threadworms that are harmless to humans and (domestic) animals as well as plants. They produce special bacteria that penetrate the larvae and poison them from the inside. The nematodes only live for a few weeks – and disappear on their own, just like the vine weevil. However, it is important to know that this watering method should ideally be used between April and May.
This is how you prevent damage caused by feeding
You can take preventive measures so that vine weevils don’t eat their fill of your plants in the first place – with neempress cake. Put 50 grams per square meter into the soil about every two months so that the active substance, which is poisonous to the pests (beetles and larvae), can penetrate the roots and leaves. However, keep in mind that you should not use the pressed neem oil if you have used nematodes. Otherwise, the toxic oil would also kill the nematodes.
One more note at the end: Vine weevils also have enemies, such as shrews and hedgehogs, moles and birds. If you lure the animals into your garden, the beetles will be fought naturally.
Sources: Federal Environment Agency, Lower Saxony Chamber of Agriculture
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