Apheloria virginiensis – a “large” millipede
This fellow was spotted on Camp Trail, Cook Forest State Park, in May of 2019. He’s a member of the Xystodesmidae, a family of millipedes which was named by O. F. Cook (no relation!) in 1895.
They don’t bite, and they don’t sting. But, according to Wikipedia, this 2-inch-plus orange & black flat-backed millipede has been “reported to secrete cyanide compounds as a defense” – so don’t touch it! If you have touched it, make sure to wash your hands, since “the toxic compounds it secretes are poisonous and can cause extreme irritation if rubbed in the eyes.”
Otherwise, these insects are harmless, and beneficial. They love damp forest floors strewn with rotting wood and host to mosses and fungi. The millipedes eat these things, and are an important part of the forest life cycle.