John,
Perhaps a systemic. Get the little beggers where they live. Maybe a topical at the same time. Have you be able to identify a source? The worst damage will come from the next generation. When they hatch under the bark, they will be feeding until they are ready to move on.

Good luck,
Vernon

I had barkbeetles on my mountain maple last year and they seemed to enjoy the protection of the wire. So they ate along behind the wire where I couldn't see them until it was too late. Now I have what looks like SERIOUS wire marks curving around the bottom of the tree trunk. I got rid of the bugs with a commercial spray (they die quickly) and am now air layering off the top of the tree. Moral to the story: Kill them quick!!

Wags