I think you are correct..White-lined sphinx. They can appear in great numbers. Kind of strange though I've only seen adults maybe 5 times in 10 years here in Phoenix.

How long they last depends on how much food you have for them. When they've had enough they burrow into the ground to change into a moth. If they run out of food they move to a new area. They do eat weeds so that's a plus.

Thanx .. I didn't know they burrowed
I don't know what they are eating all the plants look fine
This is a 5 gallon bucket of them that I fished out of my
Pond !

Another shot of pond

Wow. Your fish aren't eating them...or too full? Apparently they are edible. You could dry them in the sun to feed to the fish later.

They're suppose to eat pretty much everything including spruge and purslane. However don't have a rep for hurting crops.

They eat almost anything ... if they run out of food they will migrate in search of it.

Adults are "hummingbird moths" - night flying big moths that hover over flowers like verbena and 4 O'Clocks

Wow! Amazing, and kinda gross, pics! Thanks for posting them! Yup, they're definitely white lined sphinx moth caterpillars, and a lot of them! I have three or four in my garden this year and was happy to have them. I would NOT be happy with a five gallon bucket of them (or even a half gallon bucket!). Closely related to good old tomato hornworm caterpillars which become sphinx moths. If they're really bothering you and damaging your plants, you can spray your plants with Bt, the natural bacterium that is parasitic on them. It won't hurt bees etc., just kills caterpillars.

I saw quite a few of these down at the Boyce Thompson Arboretum two weeks ago.

I'm fascinated and grossed out! Hah. Let us know what you do and how it works out.

Happy gardening,
Grant