Yes, I've read that they have a pretty good protective treatment, to prevent the borers from getting into a live tree. The problem now is with stockpiled boards. If one infected board is put in a room with other clean boards, within a few months, they will get into all the other boards too.
In my own shop, I had boards that were more than 10 feet apart, where the borers apparently sniffed them out and walked over to the other boards. In 2008-2009, I had to get rid of every single piece of ash in my shop. Even some small pieces of ash that I used for fixtures and templates got infested. It was terrible. Fortunately, they never got into my collection of finished Scroll Basses that I built with ash bodies. It appears that if the ash is sealed up with a good finish, they aren't interested.
They only get into ash. I had ash boards in the middle of a stack of boards of poplar, maple, mahogany, etc. They found and infested the ash boards, but didn't touch the others. And once they are into a board, you cannot get them out of it. Chemical, heat treatment, IR treatment, sealing it in vacuum, none of that works. The eggs are in there and they will survive almost anything. Next spring, a fresh squadron of borers are munching away. You have to burn the board or send it to the landfill.
I still have the two Scroll Bass bodies that got infested, wrapped in plastic and sealed in a box. I haven't looked at them in a few years, but for at least 6 years the borers still kept hatching every spring. Those two bodies look like cheese, hundreds of holes. Natural chambering.