Eight different Lepidopteran pests were selected for the molecular studies. The genomic DNA of these selected species was isolated by the Maggenome method, and their quantity and quality were tested through agarose gel electrophoresis. In the present study Cytochrome oxidase subunit I (COI) gene of eight species of butterflies was sequenced, aligned and used to construct phylogenetic trees. The molecular identification of these eight species was confirmed by comparing the related sequences in the National Centre for Biotechnology Information (NCBI) GenBank. A phylogenetic tree was constructed for the 8 COI gene sequences of different butterflies by the Neighbour-Joining method employing Bootstrap type. Thus the results besides showing the relationships and difference between the selected species also signify the merits of molecular phylogenetic studies based on evolutionarily conserved genes such as Cytochrome oxidase which predicts the phylogeny in contrast to the conventional methods which are based on visible traits like morphology, wing pattern, color, etc.