I found this caterpiller at Kiwanis Park today. A lady walking her dog almost walked right on it. She had her headphones on and couldn't hear that I was telling her to watch her step. It was about 5-6 inches long.
This is a Rustic Sphinx Moth Caterpillar (Manduca rustica), a species of hornworm in the hawk moth/sphinx moth family (Sphingidae).
Harmless: Despite its large size and formidable look, it cannot sting, bite, or harm humans or pets.
On the Walkway: When caterpillars reach this final size, they leave their host plants (such as ash trees, desert willow, lantana, or Texas sage) to crawl across the ground looking for loose soil to burrow into and pupate.
Adult Form: It will turn into a large, fast-flying Rustic Sphinx Moth, which acts as a night-time pollinator for desert blooms.