Persons proposing to move plant pests into or through the United States from any place outside thereof, or from any Territory or possession into or through any other Territory or possession, or the Continental United States, by baggage, shall show the permit authorizing the movement to the inspector upon arrival at the port where the baggage is inspected. The conditions specified for the movement must be observed. The inspector will insure that the movement is handled in accordance with the terms of the permit. If it is necessary to move the plant pest to another place for clearance, the owner will be responsible for all costs incidental to such forwarding. Pending forwarding, the inspector will specify and supervise the application of safeguards against danger of plant pest dissemination and may retain custody of the pests until forwarded.