Karl Schroeder, thanks for your informative letter.

Does anybody ever notice that every species is "invasive," in that its range is always acquired at the expense of one or more competitors?  In Washington State, the Himalayan blackberry is labeled both a noxious weed and an invasive species.  Never mind that the whole western half of the state has been covered with them for over a century.  Never mind that they produce a very usable--indeed, delicious--fruit.  Just bring fire and fury on those noxious aliens!