§ 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.