The wine weevil is the number one pest when it comes to bonsai. This vile beast has the ability to destroy your whole collection!
The signs to look out for are semi-circular holes on the leaves indicating that a weevil has been chewing on them during the night. They prefer to come out in the night time to feast on the leaves so they can be hard to spot. The best way to find out if you have any is to keep a check on your leaves for marks. Spend time looking after your bonsai and you will be able to spot these easily.
However the adult vine weevil might make your bonsai look ugly by chewing on the leaves but it is not the one that will kill them. They lay eggs in the soil of the pot and their larvae eat the roots of the plant which will lead to their death. Because they live underground they are impossible to spot which is why it’s important to keep an eye out for the adults.
What can you do to treat them?
If you discover vine weevils or think you can see their marks on the leaves you must spray your whole collection with parasitic nematodes. These are microscopic worms which will kill the larvae.