Well, if you came here to NZ with instruments that looked as if they were NOT professionally made, you would need a certificate of sterilisation, or you could pay to have them taken away, sterilised, and sent on to you. With a certificate. Radiation, heat treatment, etc. We too protect our agriculture, and passengers could be lying.

One of our constant TV programmes is about border security by the Agriculture and Fisheries authority, and passengers come in with things made from the likes of gourds and raw wood, -or grass, in the case of that flute,- and not by a luthier but in a village workshop, and they have to get them sterilised or they're taken away from them. Same deal for fishing tackle and farm equipment, particularly from some parts of the world. There are as many dogs sniffing out food and plant products as there are drug dogs at the airports here.
DON'T bring unprocessed food here, and DON'T lie about it.

On the other hand, people who know the system just get the certificate.
I saw one programme where a hunter brought in a recently killed bearskin and other trophies with no trouble at all. He was local and he'd followed the procedure.