Yes, good point, Java - and good example! I remember reading about the Spartina plague in the SF Bay.

It strikes me that it's probably impossible to keep "their" flora and fauna from invading "ours" over the long run. I guess the difficulty is that it now happens so fast - for man-made reasons - that the natives don't have time to adapt to the invasion (e.g. evolve protective mechanisms). Is this anywhere near the right concept?

Diane