Probably will be easier to do just using functions in mySQL, with less brain damage. As an example, I found this in the mySQL online documentation, which may suggest a course for you (first example on that page):

mysql> SELECT something FROM tbl_name
           WHERE TO_DAYS(NOW()) - TO_DAYS(date_col) <= 30;
[download]

Using that as a basis, you could do something like:

mysql> DELETE FROM tbl_name 
           WHERE TO_DAYS(NOW()) - TO_DAYS(date_col) > 31;
[download]

Hope that helps. (The use of that code from a perl script is left as an exercise for the reader. :)