This book on the “Adipokinetic Neuropeptide Hormones of Orthaga exvinacea”, encompass results of our investigations on the structure and functions of adipokinetic neuropeptide hormones of the mango leaf webber, Orthaga exvinacea, a pest infesting mango leaves in India, especially south India. The methodology involved dissecting out the retrocerebral complex of several insects, extracting peptides into methanol, and using this extract for bioassays and structural characterization studies. Heterologous in vivo bioassays (in Iphita limbata) and in vitro incubations of the hormones confirmed their role in the mobilization/ release of lipids, carbohydrates and proteins from the fat body of insects. Structural studies involved HPLC separation of active components and subsequent mass spectroscopy (MALDI-TOF/MS/MS) of the peptides. The structure of the peptide was compared with those of other peptides from other insects and phylogenetic relationships were attempted. The effects of the adipokinetic peptide from insect on vertebrate liver also ignites interest in the application of these peptides or their analogues in obesity treatment in human beings.