Can't help you, but I have some questions that I'd like to see
addressed by anyone kind enough to answer your post:

1) Would pouring an oil (vegetable or some other specific oil)) into
the hole have driven out the pest?

2) It seems like the infestation was limited in the number of pests.
Given that the tree is for bonsai and still in a container, was an
insecticide really necessary?

3) Is the tree still viable for long term bonsai? Won't the burrowed
hard wood no be likely to rot and the tree eventually collapse in on
itself?

Today again same pile and it was MOVING so I tried to grab what was
inside no way ,I took a file a thin long one for goldsmith ( rat tail
is called) and chased the host inside the wood in a straight tunnel 2"
deep !!!!! ( I could not fo further with the file if it was making a
curve)