Could anyone help me in identifying what kind of pest or disease does my Ligustrum have? It happens every winter when I keep the Bonsai indoor. What could be the possible cure and treatment for it? It appears on the new branches and leaves a white coating which in some cases brings the part to slowly dye. Thanks in advance.

It's hard to say if you have spider mites or not from the pictures. I can't tell if their is a glare on the leaves or if it is webbing.
Besides that how long have you had the Privet and how often do you water it? (Just common problem I also see here)

Gianfrancesco wrote:

Could anyone help me in identifying what kind of pest or disease does my Ligustrum have? It happens every winter when I keep the Bonsai indoor. What could be the possible cure and treatment for it? It appears on the new branches and leaves a white coating which in some cases brings the part to slowly dye. Thanks in advance.

Take a white piece of paper and a magnifying glass. Put the white paper under the leaves and shake the branches a bit. If you have mites, they will fall on the white paper. and you can take a better look at them with the magnifying glass.