I had a really great lunch with an old friend last week, and we talked a lot about white pine blister rust. If you aren't familiar with it, white pine blister rust is one of the oldest, and most widespread, non-native forest pests in North America. It was introduced just at the dawn of the 1900s, and it is still killing pine trees all over our continent to this day.
One of the things that we talked about was, at a grand scale, the genetics of invasive species. And I explained that in my opinion, moving firewood of any sort, ever, is a bad idea- not only because it might create new infestations of non-native pests, but also because it could result in the non-natural movement, colonization, and hybridization of native pests. White pine blister rust is pretty much everywhere, but that doesn't make it OK to move infested pines, in my book. And he agreed, and said...
"If you think about it, there are two possible outcomes of the movement of any sort of pest; nothing, or something bad."
And I think this is a very good way of summing it up. If you move firewood, most often, nothing comes of it. That's true. But every once in a while, something bad could happen. And it is worth noting that nothing good (in a biological sense) could happen from moving firewood. You won't ever make a less harmful forest pest- that's biologically impossible in this context- but you could create new populations, or hybrids, or... something else, bad.