Interspecific attraction between Earias vittella and Earias insulana was studied by conducting sex pheromone bioassays and by making visual observations on the behaviour of individual interspecific pairs. Olfactometer bioassays using virgin “calling” females revealed interspecific attraction amongst about 10% males. In bioassays using female sex pheromone, E. insulana did not attract any E. vittella males, but the E. vittella female sex pheromone attracted 8.7% interspecific males. Electroantennogram recordings revealed detection of interspecific sex pheromones by antennae of males of both the species. When kept at a close range and allowed free access to interspecific females, more than 50% of E. insulana males courted and copulated with E. vittella females, but incidence of such courting and copulation was negligible in the reciprocal cross. In both the cases, there was no interspecific insemination. These studies suggested that dissimilarities in: (a) sex pheromone components or their ratio, (b) courtship behaviour and (c) sperm transfer mechanism play a role in the reproductive isolation of these two species.