He and friends like to eat plum leaves.
Schizura unicornis, the Unicorn Caterpillar; becomes the Unicorn Prominent moth as an adult. Your top view does not reveal the horn.
^ best-matched image; click on Info tab for specifics
^ shows North America distribution
^ mentions Texas and plum
That’s him! Thanks. I’ve never seen one before. There was about seven of them and they were stripping all the leaves on a Santa Rosa Plum.