Synopsis Diversity is the first comprehensive monographic work that puts forward an up-to-date account of taxonomic knowledge regarding Blennocampinae, Heterarthrinae and Nematinae. Till about two decades back very meagre taxonomic knowledge regarding these three subfamilies was widely known : only 14 genera covering 22 species from the faunistic limits of India. However, a substantial contribution has been made by Saini & his co-workers during the last 23 years wherein they brought to light 15 additional genera covering 85 species (both new as well as first record). Nevertheless, to accomplish this arduous task, a thorough survey of all high altitude forest regions along the entire Himalayan belt was made.This work provides elaborate identification keys, detailed catalogue, illustrations and diagnostic features of all taxa so far recorded from India under these three subfamilies. Since sub-order Symphyta (Hymenoptera) was not covered under "Fauna of British India" volumes, so due to lack of very basic know-how regarding this insect group any further taxonomic work particularly by indian workers remained stranded.