We too in Canada are losing our trees to the Emerald Ash Borer, once infected the trees die, there is no fix except to remove the tree. We had so many removed last year in our neighborhood. The other nasty is the Asian Longhorn Beetle. It's about the size of a nickel - who uses those today? But there are restrictions regarding this beetle - wood can't be delivered from one place to another in some cases. I believe these nasties kill Maple trees. Our native tree! The one I war against the most is the Japanese Beetle. We had such a huge infestation for a couple of years. The beetles do not have a predator - birds do not like them, skunks and raccoons don't eat their larvae. We lost most of our bushes and a few trees and all of our fruit trees to this beetle. The are attracted to mostly red foilage and fruits. Some people use a Japanese Beetle trap - it looks like a yellow flying tube...attracts them from over 1km - that's the problem. The are attracting them to our area with this trap but the beetles find other gardens on the way.
The only way to get rid of them is to hand pick them from the leaves in the morning and late afternoon. They are disgusting but it's the only way. Carry a bucket of warm soapy water and knock them in. The grubs from these are a lot bigger than other grubs. We lost our lawn, grape vine, peach tree, cherry tree, Japanese Maple, Burning Bush, Holly bushes, Hydrangea, Peonies and more. Ick Ick Ick!!!!
The other remedy is plant native plants and buy nothing that has a hybrid or has come from another country or a non native area....that's what we did and didn't have one beetle this year.