I stumbled across your site while trying to find out what these little critters are called. I vaguely remember being told as a child that they are firebugs. The ones that look alike were all over the place being naughty. The smaller ones with less distinctive designs were just stumbling around. These were spotted under a shady tree on the side of a salt water canal in Miami Beach–around noon today. Thanks for the cool site!
Thanks for contributing a new species to our site. These are Cotton Stainers, Dysdercus andreae. They are True Bugs in the family Pyrrhocoridae, the Red Bugs. They are found in Florida and the West Indies. The common name comes from the fact that they would actually stain cotton while feeding, ruining the quality of the product.