Dispersal and distribution of Calliphoridae (Diptera) immatures from animal carcasses in southern Louisiana.

Spatial distributions of calliphorid pupae (based on adult emergence) from swine carcasses located in woods and pasture were determined during 4 seasons in southern Louisiana. Adult emergence was substantially greater in pastures than woods for all seasons except winter. Secondary screwworm, Cochliomyia macellaria (F.), was the predominant calliphorid species collected ( > 95%) during summer and fall; whereas, black blow fly, Phormia regina (Meigen), was the primary species (86%) during spring. The highest densities of calliphorid pupae per square meter were located within 0.9 m of the animal carcasses in the woods and the pasture (summer); however, the number of calliphorid pupae per square meter during the summer was substantially greater in the pastures than in the woods (2,370/m2 compared with 77/m2). Postfeeding calliphorid larvae preferred to disperse toward the southeastern quadrant during summer and spring and toward the southeastern to southwestern quadrants in fall. The winter evaluation period was the most prolonged (85 d), had the least number of emergent adults (only 6-11% of the populations that emerged in the other seasons), and consisted of predominantly, Phaenicia sericata (Meigen).