Anyone else going to give up on sap bags?

I only tap 20 or so trees per year so have been using sap bags with home made pvc holders. This year I've had to replace almost half of my bags due to holes created by forest critters. Usually I get 3 or 4 I need to replace, but this year it's way up. I even have a strip of duct tape along the bottom to try to prevent nibbling at the corners, but even that isn't helping.

Shame since I bought bags in bulk last year so I have a big supply.

Any other tips for keeping the bags from being nibbled before I switch to pails on the ground next year?