Otiorhynchus: How to exterminate black vine weevil naturally

Do you have rhododendrons, azaleas, cherry laurel or other plants at home? If you do, you should know that these plants may get attacked by some type of Otiorhynchus pests sooner or later. The most famous are weevils of the Curculionidae family. In spring and autumn, these bugs feast on plant roots and leaves. In the following lines, we shall tell you what weevils are, how they can get into your garden and how you can fight them.

Bite-outs on leaves – the first sign of destruction

If you see semicircular bite-outs on rhododendrons, azaleas, cherry laurels or similar plants chances are that your plants have been attacked by weevils. Adult beetles are usually black and they possess a huge appetite. They can literally destroy all leaves they find and attacked plans of bushes gradually turn yellow, wither and die.

Photo: Radek Štěpán

You may have brought them home from a garden store

Larvae can easily hide in containers that are used for plant transport but they also live happily in forest nurseries or parks, and in relatively strong colonies.

Creatures of the night

You can hardly see these creatures during the day. But it is a different story at night. The best way to catch them is to set up the following trap. Place a board near the attacked plant and spray the board with water. When you lift it in the morning, you should see several bugs underneath.

Photo: Radek Štěpán

What these bugs destroy

Otiorhynchus may destroy many different deciduous trees. These often include:

• hibiscus,
• ivy,
• azaleas,
• rhododendrons,
• hellebore,
• cherry laurel,
• and many other plants.

Photo: Opuntia: https://commons.wikimedia.org/wiki/File:Otiorhynchus_sulcatus_PICT3373.jpg

Parasitic nematodes as the solution

If you prefer “a manual fight”, which means picking individual bugs by hand, you will do a lot of hard work but you will never get rid of them all. The best way is to use parasitic nematodes. These are small microscopic organisms that attack the larvae of weevils. When nematodes get into the larva, it takes about 48 hours before they die. You dissolve the nematodes in water and pour the mixture around the plant. The most efficient way is to combine nematodes and chemicals. There are different insecticides that you can use.

Preview photo Martin Cooper: https://commons.wikimedia.org/wiki/File:Vine_Weevil_(Otiorhynchus_sulcatus).jpg