Possible Light at the End of the Polyphagous Shot Hole Borer Tunnel?

Dr. Akif Eskalen pointing to  PSHB attacking a tree at the Arboretum.  

The two different unknown species of Polyphagous Shot Hole Borer (s),  that until now have had free reign tunneling into and destroying such California native trees as Sycamore, Box Elder and Red Willow, may be seeing leaner days ahead now that a new parasitic wasp that appears to attack them and keep their numbers under control has been discovered. You can read more about it here.
In the meantime (it can take up to two years for the parasite to be tested, bred and released) if you have a Sycamore tree that you want to save from the beetle then spraying a contact insecticide mixed with a bark penetrant every 6-8 weeks on the bark of the trunk and larger branches may be the only way to save it. The treatment (which should be done by professionals with a bucket truck), is expensive, but I've seen it keep the infestation levels down on trees that, if lost, could drop the price of the properties containing them by 10's of thousands of dollars.