These instars were photographed in 1987 in Cavern A, on the right hand side of the walkway before reaching the skylight, after a couple of days of rain, and the guano was very wet. Click on the highlighted area see it enlarged. Based on the shape of the bodies relative to those in the other images, I would like to suggest again that these are neither Periplaneta species. Might these be Pycnoscelus striatus?