Mass spectrometric methods were used for the fi rst time to reveal the sequences of peptide orthologs from a large number of insects species, focussing on cockroaches. Sequence data of CAPA peptides (three periviscerokinins, pyrokinin) were obtained from single specimens, which led to the reconstruction of phylogenetic trees. The results are compared with the current grouping of the respective species, based primarily on morphological characteristics. The effi cacy of the mass spectrometric analyses of peptide sequences makes it possible that the described method is suitable to complement morphological and genomic analyses for the reconstruction of phylogenetic relationships.