An insect from the archives...
As you can tell from the bright orange and black warning coloration, it is likely this species is chemically protected. How noxious a given caterpillar is, however, depends on whether it feeds on certain chemically-defended host plants.
Another species, Harris' checkerspot, has caterpillars that are orange and black as well. They look very similar and are apparently mimics.
You can find photographs of Baltimore checkerspot host plants, life cycle, and a link to coloring pages at the Maryland Dept. of Natural Resources.