The interaction of several classes of pyrokinin-like neuropeptides with their respective expressed receptors is investigated from a structural and conformational perspective. The discussion concerns a broad class of insect neuropeptides that represent products of the Capa-gene. Structural and conformational aspects critical to the interaction of the pyrokinin/PBAN class of neuropeptides and another Capa-gene product, the ecdysis-triggering hormone (ETH), with respective, expressed lepidopteran receptors are described. These ligand-receptor interactions are compared with the structural and conformational requirements for diuretic activity of the CAP2b/PVK sub-class of pyrokinin-like neuropeptides, also of the broad Capa category, in a dipteran. Insect neuropeptides of the classes selected for this discussion are implicated in the regulation of critical processes in pest insects. However, they suffer from a relative lack of biostability and bioavailability that limits their effectiveness as tools for neuroendocrinologists and as pest management agents. Biostable/bioavailable mimetic analog development of insect neuropeptides will be facilitated by a through understanding of structural/conformational aspects of the interaction with their receptors.