No, but seriously, I remember learning about like Gypsy moths or something like that, how they were brought over from Europe or something and they escaped from the place where they were being kept. Once in the wild they reproduced like mad and began to ruin the environment. Or something like that. (This was wayyy back in 3rd grade so my memory is a bit spotty) Also, a certain type of ivy (I think it's the kind we have tons in our yard..oops) kills trees, bushes, etc. It overruns just about every plant it runs into and wraps around and around and kills it. Not instantly, of course. Over time.
Now I know corns seem so cute and cool and wonderful, but I do understand why they made it illegal to bring organisms that are not native to Australia because what kind of effect they might have on the environment. Not like we haven't killed the environment enough already, but you know. I guess it makes us humans feel better.