Find some sort of smell based deterrent to avoid complications, threads do not sound like a great thing for cats to eat.
If this helps, I don't know whether mine has Pica... I think she just wants to get my attention or to punish me for ignoring her while I work... but she eats anything that has a crinkly plastic surrounding it (she lickts it to distraction and then tries to eat it). She also hunts down plasticky post-it bookmarks, the small ones, she smells them from far away - must be the glue - and digs in the library and pushes books out of the way to reach at them. My solution: got citronella essential oil and put some drops in pieces of fabric which I have then left on the areas she likes to eat from. Has worked a treat.
Now my study room stinks of citronella.
Hate it, but she hates it more.
She is not eating all the wrappers or the post its anymore [#littlevictorydance]
*** caveat: in case the oil has phenols or something dangerous for kitties - I checked all over before using this deterrent - just make sure the cat will not be licking or ingesting this. One site recommended it (
https://www.vetinfo.com/using-citronell ... llent.html ) but my approach is to just add a couple of drops in a small rag and put it inside a small burlap bag which I leave on the relevant area of the shelf. That way can only smell it and not ingest anything.