Abstract
Blood from the larval, prepupal, and early pupal stages of Calliphora augttr' (F.) contains the same 18 free amino acids. In addition, hydroxyproline is present in larval and prepupal blood. The quantitative differenccs in the concent,ratiolls of these amino acids arc reported. Larval blood has the highest free amino acid content (6'6 mgjml) followcd by early pupal blood (4'6 mgjml) and prepnpal blood (3'3 mgjml). As the larva matures to the prepupa, the greatest decreases occm in the concentrations in the blood of alanine, glutamic acid, glutamine, glycine, proline, and tyrosine. The metabolic significance of these changes are discussed.