Hi!

I need help in identifying these insects/arachnids/whatever that are infestating my bonsai. I have taken a sample from a leaf and took pictures with magnifying lents.

I also need help in what treat this menace.

Thank you

the thickish ones are aphids.
The other ones could be borers

TReat.. You could spray with general purpose insecticide. Or, if your tree is in good health, leave them alone and lat nature solve it. Killing stuff only leads to bigger infestations as your natural predators are also killed.