Question
About 9 years ago we transplanted two sugar maple trees from the Owen Sound area to our yard on the escarpment in the niagara Falls area.  Last year I noticed one branch of the one tree had died (leaves turned colour early and no new growth this spring).  This year the same thing happened to the other tree and I found a small hole bored in the bark about eye level and around the hole the trunk was hollow.  This was right beneath the section of the tree that has died. I really don't want to lose either of my trees.  Can I stop this pest?

Answer
Sounds like it could be borers. I would spray the trunk and limbs with an insecticide called merit. this will kill the insect in the trunk and prevent others from attacking. Borers attack trees under stress. I would fertilize the tree with 10-10-10 fertilizer scattered around the tree and watered in good. This will add growth to the roots. Also if you have not done so I would mulch around the tree with not more than 3 inches deep of organic mulch not piled up on the trunk. This will help hold moisture around the roots.
You should be able to find the insecticide at your local nursery/garden type store.