caterpillar id needed

This is a small critter. It's munching on my parsley. Know what it is?

That's a giant swallowtail. He'll turn into a beautiful butterfly...

Help PLEASE! See that white section on the back of the caterpiller? That is the size and color of whatever is killing my plants. Pure white, looks like spiky hairs all over it and makes a blob of white foamy looking stuff. Now I see that the white foamy stuff has hatched out white aphid-looking things. My camera is not good enough for close ups, but I'll try to post a pix.
This is for size:

This is a bad close-up.

Are they spittle bugs? Is the white foam wet like spit?

This is what happened to my Portulaca, where it started and is now spreading to other plants.

Pati, I'm thinking you might have a type of wooly aphid. I have this on my apple trees. It does spread so easily. I'm cutting out every leaf and branch that has any on it and putting it immediately in the trash. A friend got some on his indoor Jade plants. All but one he tossed! O, neither one of us spray. Don't want to hurt beneficials.

Check out the recognizable stage of this catepillar. What a beauty!
koko

He's a beauty even before he learns to fly hunh.? Next he has to spin a coccoon. See if you can keep track of him. Love these posts where we get to watch all this stuff happening. ~Blooms

Oh my goodness, I'm so embarrassed. I was in such a panic about my Portulaca, I posted all over DG's forums. Now I realize I didn't come back here to clear my question. It is a Mealy Bug and here is the site I found on GOOGLE to identify it. It is really nasty stuff and I have isolated the plants to keep it from spreading. It got to one trailing Lantana before I caught it.
Pati
http://www.greengardener.co.uk/mealy.htm

P.S. If I have to have a "garden foe", why can't it be as pretty as the caterpillar. *grin*

BTW kokopelli the cat on your parsley is from the Black Swallowtail and not Giant Swallowtail.
It's often very difficult to determine the species with early instar cats.
I attached a pic of an Black Swallowtail Butterfly.

Milan

PC,
Your right. I first had them in my greenhouse a couple of years. I got to see them from egg to butterfly. That greenhouse had such an amazing balanced environment. I also had ladybugs and
aphids, and wasps showed up with the whiteflies. The Black Swallowtail is a beaut.

PS, I know how nasty those mealy bugs can make things. Sorry you lost your portulaca, but glad you got the pests cleaned up.
koko