I used to work at a cabinet shop years ago, during a pp beetle outbreak. What we learned back then is the eggs are in the wood and can lay dormant for years. When they decide the conditions are right, they spring to life and hatch. They eat thier way out of the wood, lay more eggs on the wood and die. Your not going to ever get anyone to claim responsibility for the damage they cause. It's wood, it's life. You'll notice most of them come out of a finished peice of wood. That means they were in there long before anyone worked on it. They got in there while still in the woods. A fact of life. Part of owning real wood. Spraying them won't do anything. When they are inside the wood, they are protected. Once they are outside, they are destined to die anyway.