Technical Abstract: The cotton fleahopper, Pseudatomoscelis seriatus (Reuter), is an economically important pest of cotton, and increasing concerns over resistance and safety issues associated with traditional insecticide applications have led to an interest in research on novel, alternative strategies to control them. This requires a more basic understanding of the neurohormonal system that regulates important physiological properties of the fleahopper; e.g. the expression of specific messenger molecules such as neuropeptides. A peptidomic study of neural tissues from the fleahopper led to the first identification of the sequences of native neuropeptides. These include the following neuropeptide classes: the corazonin, short neuropeptide F (sNPF), myosuppressin, CAPA-pyrokinin and -PVK peptides. The CAPA-pyrokinin, sNPF, and CAPA-PVK peptides represented novel sequences. A comparison of fleahopper neuropeptides with those of related heteropteran species indicates that they are quite different. Myosuppressin in the fleahopper is found not only in an N-terminal pyroglutamate form, but also in an unblocked form that has not been found in any other insect. The sNPF of P. seriatus shows, among others, a novel substitution of Leu with Phe within the C-terminal region; a modification that sets it apart from the known sNPFs of not only other Heteroptera but of other arthropod species as well. The identity of the neuropeptides native to the fleahopper can aid in the potential development of biostable, bioavailable mimetic agonists and antagonists capable of disrupting the physiological functions that these neuropeptides regulate.