I found this monarch caterpillar on the fence post. This is likely to be the same caterpillar I found on the ground near the green waste bin. Meaning it was probably on some of the shrubbery trimmed out of the jungle out back and put into the green waste. I always check for caterpillars when trimming; didn't see any while trimming, not even signs of them. Oops.
Anyway, I had picked it up from the concrete driveway and put it on a milkweed plant hoping for its survival. There has been meager monarch sign for months . . . this must be the same caterpillar. A little while after these photos were taken, the monarch had gone. Looked around, couldn't find any sign of it.