It shall be unlawful for any person or firm to engage in the business or occupation of pruning, treating or removing trees within the city without first applying for and procuring a license; provided, however, that no license shall be required of any public service company or city employee doing such work in the pursuit of their public service endeavors. Before any license shall be issued, each applicant shall first file evidence of possession of liability insurance in the minimum amounts of $50,000 for bodily injury and $100,000 property damage, indemnifying the city or any person injured or damaged resulting from the pursuit of such endeavors as herein described. There shall be no license fee required for an arborist’s license.