Found several of these large caterpillars feasting on my Mexican flame vine (senecio confusus) What are they? South Florida. I have had the vine for years and never saw this critter. Thanks
This appears to be a dark morph of a salt marsh moth caterpillar - Estigmene acrea; see https://www.backyardnature.net/n/a/acrea.htm
Caterpillars of this species can appear in a wide variety of coloration, from pale yellow to nearly all black.