The locomotor responses of larval C. splendens and C. virgo were considered in interactions between conspecific and heterospecific individuals. Quantitative species-specific differences in the postures and movements of contacting individuals and qualitative species-specific differences in the application of these postures and movements in contacts with conspecific and heterospecific individuals were revealed. The results obtained give grounds for inferring a marked ability of the 2 spp. to discriminate conspecific from heterospecific individuals. The mechanism of this discrimination is not understood.