You might be able to kill the larvae just by leaving a few sticks at a time under car front and back windows on a sunny day. Metal surfaces under summer sun can heat to over 160F. Assuming you have a sunny location, make a long box, several layers of cardboard will do, and paint or surface the inside w. black. Lay in the branches, and cover w. glass, sealing as well as possible.I have done a lot of research on this and have tried several things.
Here is what I found...
The wood must be heated to a minimum of 150 degrees F. to kill the larvae.
I will put smaller pieces in a paper bag and microwave them for a minute at a time until the wood is uncomfortable to hold.
Larger/longer pieces need a steam tube or some kind of enclosed box and a heat source.
I am working on ideas for a larger box because I have some beautiful sticks that I need to save at all cost.
Borax is supposed to work by drying out the larvae and it is abrasive enough to their digestive system that it kills them from the inside.
I am going to try mixing borax with water and use a syringe to inject it into the holes and tunnels.
I know people who use insecticides and other harsh chemicals and don't worry about the dust.
But I have contacted the companies that make the stuff and they have said that it should never be used this way.
"Absolutely Not" was used quite a bit in the conversations.
I can understand some saying to just destroy the sticks and don't take the chance.
But I can't do that to a really nice stick if I can find any way to save it.
I hope this helps someone.
I made a solar oven that way which would reach 210F in about 2 hours.