One of the defining characteristics of the dipteran group Calliphoridae (blowflies) is the necessity to lay eggs on a proteinacious substrate, usually the living or necrotic tissue of an animal host; larvae then develop by feeding on this protein-rich matter. Within forensic entomology, blowflies are recognized as some of the most important and robust indicator species, as they are usually among the first insects to colonize a body after death, often within hours. Typically, the immature stages of blowflies, particularly larvae, are collected at a suspected crime scene and are used to establish the minimum postmortem interval (PMI), using larval age as a form of "biological clock." Accurate species determination is essential to PMI calculations, since growth and development rates can be highly species-specific; consequently, forensic entomologists are increasingly favoring molecular methods of identification. Currently, DNA-sequenced-based analysis is the only routinely used molecular-based species identification tool. Due to the presence of several different styles of parasitism within Calliporidae (saprophage, obligate, and facultative), blowfly speciation is likely to have been accompanied by the evolution of different larval protein that relate to their differing life-history strategies. The authors identified antigenic markers capable of being adapted for use in the development of a protein-based species-specific diagnostic test. Four forensically important blowfly species were initially chosen for comparison. The descriptions of materials and methods used describe the samples used, larval protein preparation, rabbit polyclonal antibody production, and gel electrophoresis and Western blotting. 2 figures and 30 references