Perhaps if you give him his own pot of grass to chew on he'll stop eating
your plants and other stuff. Petsmart sometimes has already growing pots
of grass and they always have the seed kits for "kitty grass".  

I don't understand the whole thing, but cats seem to have an instinctive
need for a bit of roughage. They might be after the trace minerals in the
grass or maybe it just helps them pass the hair through the system
instead gacking up hairballs.  

Mine sometimes eat the grass and then throw it up on the carpet. Icky,
but safer than letting them eat string or plastic. (George would go after
bubble wrap and other bits of plastic if I don't keep it out of his
reach.)

I suspect you will be bombarded by this idea/fact as the day goes
on, that eating string can be deadly too. I think the warnings are
sincere and they do make perfect sense to me after giving it some
thought but fortunately having no personal experience with the
problem. Considering the horrid conceivable consequence, something
like seeing a piece of dental floss lying around alarms me. It has
to do with a cat's need to continue swallowing when a string is
lodged in its throat and then the swallowed length of string getting
tied up and cutting into the cat's intestines. Definitely not a
pretty thought.

Good luck.

He's also been chomping on my spider

House plants can be toxic and deadly to cats, pointsetta's for example.
You may want to check each plant before "feeding" to kitty.

String eating can be fatal (and an agonizingly painfully slow demise)
to cats and dogs. Never pull the string from the bung hole, just let it
pass. Have Vet. check if needed.

Do anything necessary to stop this activity today! Good thing you found
out about it here the easy way! I'm Happy "Boots" has a owner who
cares! Great Job!

Karl.

If you see a piece of string hanging out of his butt or looped around the
base of his tongue- don't try to pull it out- the other end could be
entangled in his intestine. Most of the times, short strings will pass
through the intestines without any problems unless one end of the string
becomes snagged at the pylorus.

Number 11 in the diagram (pyloric sphincter) is the most common spot where
strings get snagged:

http://www.maxshouse.com/anatomical_diagrams/Feline_Digestive_Tract.jpg

If the string becomes snagged, the muscular contractions (peristalsis) that
move food through the intestines can cause the string to pleat up the
intestines and even cut through the intestinal wall.

http://www.maxshouse.com/Illustrations/String_in_intestine.jpg

String and some other materials usually don't show up on plain x-rays, so, a
contrast agent is often necessary to see them.  Even though some materials
aren't visible on x-rays, the distorted intestines are.

The most common practice is to wait a few days to see if the cat passes the
string.  I don't think that's wise because in a day or two, the string could
pleat up and cut through the intestine if one end gets snagged at the
pylorus.  If you even suspect your cat swallowed a string, I'd have him
x-rayed right away.  If the string makes it past the pylorus, there's a good
chance it will pass-but its too great a risk to wait and see.

Phil