Probably a millipede, 2-3 inches long, either black with longitudinal white stripes or white with longitudinal lack stripes.
Lowland insular tropical mesic mixed forest.
Spotted in images taken for a mushroom spotting at the same location, along the Upper Waimano Trail in south central Oahu about a half mile from the trailhead. The parts of the images containing this unintentional spotting were cropped and uploaded here as their own spotting. The focus in the crops is not sharp, but I believe I can see legs on the creature, making it a millipede, not some sort of exotic larva. However, I am not sure, because I can't find pictures online of a millipede with the black and white longitudinal coloration of whatever this is.