Nadata gibbosa
Hodges #7915
Auburn, AL
This is the larval posture when threatened
Note: Mandibles (jaws) are bright yellow with black tips, a feature of this species
Source: http://www.bugguide.net/node/view/425
Comment from bugguide.net member: My speculation is that these are the same species and the earlier photo is getting ready to pupate
(and that the dark "stripe" down the back is actually the dorsal aorta) which may explain the pinkish coloration.
Source: http://bugguide.net/node/view/793094