Unidirectional en masse larval dispersal of blow flies (Diptera: Calliphoridae)

Decomposition of carrion is a complex ecological process wherein nutrients and energy are recycled in the environment. After feeding but prior to pupation, blow fly larvae disperse from decomposing carrion, presumably to escape unfavorable microsite conditions or perhaps predation. By leaving the immediate area, larvae are effectively transporting carrion-derived nutrients throughout the ecosystem. This dispersal is generally characterized as individual-based and moving randomly from the carcass in every direction, however, non-random, en masse maggot dispersal has been documented at least twice. Here, we report another incidence of en masse blow fly larval dispersal traveling due east in a small column. At approximately 2 m, the column stopped its unidirectional path and dispersed in a radial, 360° pattern. A subsample of 5 larvae was collected, returned to the lab, and identified as Lucilia coeruleiviridis, a common blow fly often involved in carrion decomposition in nature. These observations contribute to an increasing body of evidence that migrating fly larvae do not always disperse randomly, which may have important implications for the dispersal of carrion-derived nutrients as well as interactions with blow fly predators.