Chemical factors or plant secondary metabolites (PSM) contributes towards larval host plant choice among butterflies. Significantly, such PSM are the basis of ethnomedicinal plants as recognised by traditional healers since time immemorial. A total of 27 papilionid butterflies utilizing 26 species of medicinal plants as their ovipositing substrate were observed. Graphium cloanthus, G, sarpedon, G, eurypylus (PI values: 3.873) were polyphagous species. On the contrary, G. antiphates, G. nomius, Atrophaneura polyeuctes, A. aidenous, Troides helena, (PI: 1.000) were strictly monophagous. The medicinal utilization values (U_v) of such plant species was recognised. Aristolochia indica (U_v=0.474) and Citrus medica (U_v=0.44) appeared to be the most popular medicinal plant among the proponents of ethnomedicine.