Seemed like a good idea...

...at the time.

Isn't it lovely? Himalayan balsam, an invasive weed. Now they can't get rid of it.
Who introduced it to Britain? Seemed like a good idea at the time.
Who introduced Rhododendron ponticum? Seemed like a good idea at the time.
Who introduced the grey squirrel? Seemed like a good idea at the time.
Who introduced rabbits to Australia? Seemed like a good idea at the time.
Who killed the last dodo, the last great auk? Seemed like a good idea at the time.
How long could this list go on?
How far back does it go?
Who listened to the serpent and ate the fruit? Seemed like a good idea at the time.