Multi-colored caterpillars?

Hello all...I have these caterpillars devouring a pot of Bronze Fennel, and I want to know what they are and what should I do with them? They are about an inch to two inches long, bands of black, yellow, and a light green, with black dots or specks on the yellow bands.
I'm worried that they will move to other plants in my yard once they've finished-off the Fennel, and if they touch my Aroid's, Gingers, or banana's, it's going to be war!!! I'd rather not kill them, if at all possible. Anyone know what they might be and what to do? Any help would be greatly appreciated. Thank you so much.

Grayse2

Most likely it is a Black Swallowtail Cat which is often seen on Parsley, Fennel and Dill plants. It specializes in these plants as they give them their defensive smell when disturbed (two orange "horns" protrude from head giving off an arid smell).

Attached a pic of cat in defensive pose.

And here the beautiful Black Swallowtail Butterfly.

Well you are right, PanamonCreel, it is a Swallowtail, and my husband identified it as Anise Swallowtail. Mine does not have the two little orange horns on it head, and the bands are the same color, just different in that the yellow bands have black spots or markings on them.
I've been seeing these large, black and yellow butterflies flying around the yard, and I was wondering where they were coming from because I didn't have them last year, and now I know why, it's because I didn't have the fennel or the parsley. I like them a lot, and think I will grow some just so I can keep them around. Thank you for your help. I also found another very large caterpillar, and the closest in identification is the hornworm that eats on the Sweet Potato vines, Morning Glories, and Datura's. I have him in a box right now with some of the wild MG until morning, then I"m going to let him loose in the yard so he can turn into a beautiful moth. Again, thank you for your help, and that picture of the Black Swallowtail is absolutely gorgeous!
Do they live in south, too? I'd like to have them in my yard. Happy gardening!

Grayse2

Yes you are right, it also can be cats from the Anis Swallowtail. Both Anis and Black Swallowtail cats look very similar (Black ST cat maybe more greenish) and do have the same host plants. Also the Anis Swallowtail will protrude the orange "smelly Horns" (osometeria) when threatened. Just touch them or squeeze them slightly and they'll give you the show :). Also the Black Swallowtail is distributed all over North America including CA.
If you ever look for Butterfly or Moth info, below are links for good spots to start:
http://www.npwrc.usgs.gov/resource/distr/lepid/bflyusa/bflyusa.htm
http://www.npwrc.usgs.gov/resource/distr/lepid/moths/mothsusa.htm

I NEVER thought I would say it, but that is one beautiful caterpiller!!
Pati

PanomonCreel,
That's a great site for butterflies! I was looking at the Monarch Butterfly, and I was surprised when I saw the caterpillar. I was always told that the caterpillars that are black and orange and have all the hairs or what I would call a wooly caterpillar, because I do know the correct terminology, was a monarch butterfly? Do you know which one I am talking about? I've been seeing them around my yard, and found one eating one of my Aroids, which I thought was poisonous to all critters, but apparently not. I was just curious as to which one this might be.

Grayse2

Not sure but maybe you are talking about wooly bear or tussock cats which are from various Tiger Moth species:

http://www.npwrc.usgs.gov/resource/2000/cateast/tigermot.htm