Insect and Spider Identification: Found these yesterday on Yaupon...Asps???, 1 by DATURA12

DATURA12 wrote:
Yesterday while trimming some Yaupon I kept coming upon these larvae. My first thought is that they were Asps, so I did not touch them without gloves. Everytine we made a cut we found more a total of 12. There are three distinct colors of these which I will post. Looks either they are at three different stages of instars, not sure. I think I have seen these years ago and did a little research and found out they were butterfly larvae of some species but can't remember.

Any help and especially why the three colors? Thanks