Preserved individuals are dorsally grayish olive green to live-brown; the lighter-shaded specimens are heavily mottled with large, irregular, brownish or dark blotches.

These frogs are frequently recorded from the most moist and coolest parts of caves,[1] but it appears that both adults and juveniles venture out into the forest for feeding.

[5] Development is direct[1][5] (i.e., there is no free-living larval stage[6]), with individual fecundity up to 48 eggs.

[5] Platymantis insulatus is common on all four islands it inhabits, and it is abundant when the weather is appropriate (during heavy rains).

In particular, guano mining and the quarrying of limestone are likely to harm the habitat of this species, and the populations are believed to be declining.