Section 18. Every public official having custody of any bond for the faithful performance of the duties of any office, occupation, agency or trust, requiring the approval of any court, public officer, department or board other than the governor and council, shall, except in those cases where the duty is imposed upon the director of accounts, annually in March examine into the sufficiency of every such bond, and shall, whenever at any other time there is reason to believe that any such bond has become insufficient, examine into its sufficiency. The governor shall appoint a committee of the council which shall annually in March make such examination of bonds required to be approved by the governor or by the governor and council. If a bond is found upon examination to be insufficient, the person who has examined it shall forthwith notify the principal thereof and shall require him, within thirty days after the date of such notice, to file a new bond in conformity with law. All bonds requiring the approval of the state treasurer and all bonds requiring his examination as to their sufficiency shall, when he deems it necessary, be secured by a surety company approved by the commissioner of insurance.