One of the plants growing in this "temporary" garden is a swamp rosemallow, Hibiscus moscheutos. At the moment the poor thing is under seige. The seeds are being munched on by untold numbers of a seed-eating bug called Niesthrea louisianica, and the leaves are being consumed by no less than a dozen voracious io moth caterpillars.
Are you familiar with the io moth caterpillar? If you've ever tried to pick up one of these impressive giant silkworms you're probably nodding your head emphatically at this point. These beauties pack a punch. Yep, they are one of the "stinging" caterpillars.
These two are having a eating competition...
This one is enjoying having a leaf all to itself...
And this one is giving us an up-close look at its urticaceous setae, a.k.a. stinging spines.

Stinging caterpillars don't have stingers in the conventional sense - nothing like the armament of a bee or wasp. Rather, most of the sting of the caterpillar comes from hollow spines attached to poison glands. The spines break, the toxin spreads out, the human (or other unlucky beast) says "Ouch!" and the caterpillar goes about its business.
I'm not familiar with the pupal stage of the io. I assume since they are considered to be one of the giant silkworms they spin a cocoon so I'll have to keep watch and see if I can find one. If I do, I'll be sure to share.