The F stadium larva of both sexes of Tetracanthagyna plagiata is described and figured based on exuviae from which confirmed adult specimens had been reared. Larvae were originally collected in small, slow forest streams in Singapore, and in captivity were fed on local shrimp and small fish species. The known larvae of Tetracanthagyna species, T. degorsi, T. plagiata and T. waterhousei are compared and characters for separating the three species are tabled and figured. T. plagiata larvae reared in captivity exhibited obligate ambush predation and ballistic defaecation.