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.

Woodlice are insects that we see very often in the garden. Their main purpose in life is to eat wood so should we be worried about them around our bonsai?

Well the simple answer to that is yes you should be worried if you see them in your bonsai pot. They do eat wood, but they only eat rotting wood. So it can be a bad sign if you see them in the pot near the roots. It probably means that your tree has got a bit of root rot going on.

They will not eat wood if it is not rotting so it’s a good indication that something wrong is happening under the soil.

How can we stop them eating the roots? Quite easily actually. You need to repot the tree making sure that it has got ample drainage. Drainage is vital in a bonsai pot to make sure that the roots don’t get waterlogged and end up rotting (which will attract woodlice). Be sure to repot the tree in early spring which is the best time to do so.

The symptoms of the disease “oak decline” starts off by showing the yellowing of leaves during spring and summer. The oak dies from the top branches downwards inevitably killing the whole tree in the end. The branches towards the top of the oak resemble a stags horns being bare at all times of the year.
Cankers on the trunk will then bleed a black pus-like liquid from the trunk. Oak decline stunts the trees ability to defend itself against other insects, fungi and diseases.