Biosystematic studies of 3 subfamilies of Reduviidae viz Acanthaspidinae, Harpactorinae and Piratinae have provided sufficient data for clear demarcations of these subfamilies in terms of biological, behavioural and morphological tools. Biological considerations involve incubation and stadial periods, hatchability, adult longevity, sex ratio and morphometric analyses of life stages. Behavioural parameters include nature of predators, camouflaging, death feigning, head nodding, spitting, nymphal rolling, mating and oviposition of the members of these 3 subfamilies. Information on the bioecology of 25 species, behavioural aspects of 40 species and morphological aspect of 165 species serve to adequately augment our understanding of the biosystematics of this important predatory group of insects.