I'm pretty sure this is a wheel bug, but can anyone tell me what the red protuberance is? As I was photographing him , I tried moving him with a leaf to get a better shot, and the insect moved the red things in and out.
The red protuberances are mites, either phoretic ('hitchhiking) or parasitic; not scent glands.
Sorry, Id'ing as "scent sacs" came from an article...and the same info is included in a number of other articles also.
"Scent sacs: Garman (1916) and Froeschner (1944) noted that wheel bugs, when captured, extrude (with little provocation) a pair of bright, orange-red scent sacs near the apex of the venter. These sacs give off a pungent scent. "