I contacted Abigail to ask her opinion on whether it was plausible that this larva was related to the H. trifurcata adults found in the same area. Here is a portion of her reply:

"...the wormlike one is just too wormlike. Hyperaspis, like most larvae in subfamily Scyminae, have pale bodies (yellow, pink, or gray) and short legs that may not be visible from above, but they're not elongated like that and would have visible shape/texture differences between the thorax and abdomen; that critter, whatever it is, is almost unsegmented. Hyperaspis would probably also have a waxy white coating, although immediately after molt or egg hatch they're naked."

Thanks, Peter. Makes sense to me. But poop? Here, I thought they were dining on tangerines.