After a gap of 25 years the Centre for Research in Medical Entomology (CRME) surveyed the mosquito biodiversity in the tail-end hill ranges of the Western Ghats, viz., Kanyakumari (Keeriparai) and Tirunelveli districts (Kalakkad-Mundanthurai Tiger Reserve (KMTR) and Courtallam) of Tamil Nadu between July 2010 and June 2013.  The altitude of the hills ranged from 100–950 m covered by evergreen forests.  A major emphasis was given to collect the immature stages of mosquitoes, from various breeding habitats, viz., slow flowing streams, spring pool, rocky pool, leaf axils, latex cup, tree hole, bamboo stumps, etc.  Altogether 4602 immature individuals were collected, reared individually to be identified at the adult stage.  A total of 3583 specimens belonging to 50 species classified under 21 genera and 18 subgenera were recorded.  The major vector species found in these hill ranges were Stegomyia aegypti, S. albopicta (Dengue and Chikungunya), Culex bitaeniorhynchus, C. tritaeniorhynchus (Japanese encephalitis), Downsiomyia nivea (diurnally subperiodic filariasis) and Anopheles mirans (Simian malaria) vectors were recorded.