It shall be unlawful for any child under sixteen years of age and not a resident of this Commonwealth to be employed or suffered or permitted to work in this Commonwealth in any factory or cannery, or in berry, fruit and vegetable raising and harvesting, during the time in which the laws of the state of his residence require his attendance at school: Provided, That in case of the lawful employment of such nonresident child during the summer vacation period, the employer may have fifteen days in which to discontinue the child's employment after the date at which the laws of the state of the child's residence require his return to school: And provided further, That this act shall not apply to children between the ages of fourteen and sixteen years who are qualified for such employment under the laws of the state of their residence, and who shall have complied with all the requirements of this act.