Dietary self-selection is a fundamental strategy for any foraging organism. Cockroaches such as, Rhyporabia maderae, have the ability to choose optimal food sources based on their nutritional requirements. Thus, nutrients themselves may have regulatory effects on dietary self-selection. Our study focuses on the regulation of nutritional preferences based on amino acid increases in the hemolymph. By injecting individual amino acids into starved cockroach nymphs and recording nutrient selection of protein (casein) and carbohydrate (sucrose) over a twenty-four hour period, we were able to distinguish which amino acids play a key role in dietary regulation. To date, we have seen an approximate 50% reduction in protein selection with a concurrent amplification of the amino acid DL-Β-alanine. Further investigation with thin-layer chromatography (TLC) showed this amino acid to be prevalent only in those cockroaches which have been fed ad libidum. Additionally, we have found that arginine inhibited protein selection and also existed in higher amounts in fed-state nymphs. HPLC analysis of the hemolymph of fed nymphs showed significantly higher amounts of glycine, proline and alanine. We speculate that these amino acids become active in metabolic pathways, act as neurotransmitters, regulate hormonal signals, fuse to become neuropeptides or peptide hormones, or be used as ligands for internal receptors which have a regulatory role in nutrient self-selection.