Update:
I have trapped 2 mice so far, so must assume it was them removing the Pyrethrum. If you have never grown, and more to the point "stroked", this plant you can't imagine how soft and unusual it is. The daisy flowers are good too.
What surprises me is how they climb onto my bench. It has metal angle iron legs (but some slots like "Dexion") and the greenhouse is aluminium, so not a lot to grip on. They probably climb up one of the thin lengths of aluminium channel that are bolted at an angle to keep the greenhouse square, and jump onto the bench, which was a deep plunge but is now just a box, sand only under the pots. I have noticed 2 teeth marks on a Zephyranthes seed pod too.