The emerald ash borer is a bug that is native to Asia. Its first sighting in America was in June 2002 in Canton Michigan. It came to America in shipping containers from Asia that were accidentally contaminated with the bug. The bug infested Michigan. Then Michigan accidentally sent contaminated trees to Virginia. The bug worked its way up to New York killing a lot of ash trees.
The emerald ash borer bug gets inside ash trees and lays eggs. Then the larva eat the cambium and phloem (which are things the tree needs to distribute nutrients) and that kills the tree within two years.
There are many ways to protect your ash trees from the emerald ash borer. You can have professionals come and infuse a chemical into the tree that protects it. Also you can buy a chemical that hooks to your hose and you spray around the tree. The roots suck up the chemical and the tree is protected.
The slogan “Buy it where you burn it" means that when you buy fire wood you should burn it there. If you move the wood to other places there is a risk of spreading wood bugs such as the emerald ash borer.