A critical role for Copestylum larvae (Diptera, Syrphidae) in the decomposition of cactus forests

► There was a 50% cactus mass loss during the initial (40-60 days). ► C/N has significative differences for both years of study. ► The initial increase and the maximum number of larvae corresponds with the maximum period of cactus tissue loss. ► There was a rapid loss of cactus mass with Copestylum larvae. ► Hoverflies larvae have an important role on decomposition of Isolatocereus dumortieri (columnar cacti) and in nutrient cycling.