Chinese Fringe dead, autopsy results

[Rose Mary]

One of the 3 chinese fringe trees I have had over 12 years gave up the ghost this year. It started budding out with the others, weakly and didn't finish.
Today I pulled it out of the colander to check roots. They were thick and healthy but the branches were starting to dry out.
Upon close inspection I noticed a tiny, perfectly round hole....egads the more I looked the more there were. . I started digging with a sharp knife and found a shiny black butt!
More cutting exposed larvae...some of the holes went all the way through!
I havent named the beast yet, some sort of borer but now I am afraid for my other trees as they have all been shuffled around together.
I found one hole on another of the fringe trees.
Anyone know what these are and a cure?
So far the fringe I found one hole in looks ok, but as I chased the holes on the dead one they went deep and had larvae in different vaults.

I am starting to try to find the culprit and hope it only goes after deciduous trees as I have fewer of them. If they spread to my conifers and kill this fast--
my collection would be devastated.

So when I find a name and remedy I have over a hundred potted trees to examine with a magnifyer... help!

 

[Cadillactaste]

Oh dear! Well...I pray they were only contained to this tree and no others are lost? Any others declining at this time?

 

[jacob letoile]

So i put in some landscape paper birches and they are really suseptable to borers when stressed. This is what i used:

https://www.atticusllc.com/product/quasar-8-5-sl/

With this as a surfactant:

https://helenaagri.com/products/nonionic-surfactants/kinetic/

The combination came highly recomended specifically against borers. I like it because it is a bark applied, systemic. I worry that given how much water flushes through our soil that root absorbed systemic will wash through before they can be taken up.

 

[SnowfallenGarden]

I read that borers like trees that are currently "in stress", so that may be why that 1 got killed and the other didnt. I cant remember where I Read it tho.
So spray insecticide and keep everything in shape and it will probably be fine.