File::Find will help you to find the files themselves based on criteria you define. That's already been suggested. I wanted to add one sanity-check piece of advice:

Whatever you do, make sure that while you're in your testing phases the only action you take is to print a list of delete candidates, or to generate a log file of delete candidates. That way you will have every opportunity to check to make sure that the correct files are being identified before you release dogs. I imagine many a costly mistake has been made by writing a script to act in some irrevocable way on a large data set only to find that it acted in an unintended way.

Now back to your regularly scheduled programming....