Section 3-109. Payment of wages to minor; when valid

Where a minor is in
  the employment of a person other than his parent or guardian, payment to
  such minor of his wages is valid, unless such parent or guardian  notify
  the  employer  in  writing, within thirty days after the commencement of
  such service, that such wages are claimed by such  parent  or  guardian,
  but  whenever  such  notice  is  given at any time payments to the minor
  shall not be valid for services rendered thereafter.