I'm fortunate to have a tree service guy just down the road from me (or I did as he just retired, and sold his property for development). So for any large jobs, he gets the call. I have had to take out at least 40 Ash trees on my property, due to the Emerald Ash borer - another invasive species originally imported into the US, and it made it's way North to Canada (crossed from Detroit area where it was well established to Windsor, Ontario) back in 2002.
In 2003 there was an attempt to stop it by picking the narrowest part of Southwestern Ontario, and cutting down every ash tree they could find in a 10 km swath that stretched across the entire province. Making sort of a "fire break" that they hoped it would not pass - that failed, and by 2007 they had reached my property. I tried everything I could to save the biggest trees, including spending thousands per tree to have sort of "injections" into the tree that would kill these things, done by a certified arborist - it was all in vain.
Last one was removed late last year:
This is the damage they do under the bark - it kills the tree's ability to take up water and nutrients from the soil:
It's an entirely man made problem, and the likely source has been traced to wood shipping pallets that were made of infected wood, and not properly treated to kill these pests off before being shipped all over the place. Canada and the US had a treaty exempting each other from the heat treating requirements - big mistake. By saving corporations money, we all paid the price - it has since spread much further, costing home and property owners a crapload of money, as well as municipalities..
Actions have consequences - that's really what this thread is all about.
Cheers, Al