Members of the order Diptera, including Wohlfartia, Sarcophagia, and Parasarcophagia, which feed on feces and decaying meat and fish, the larvae (maggots) of which develop in putrefying or living tissues. Maggots of the latter group produce myiasis; these include screw-worms (both primary and secondary invaders); wool maggots of sheep; botflies or skin maggots of humans and domestic animals (including warble or heel flies); head or nasal botflies of sheep and goats, horses, camels, and deer; and horse botflies (or gadflies) the larvae of which develop in the lips (egg to larva(L2) and in the stomach (Giardia intestinalis) and duodenum (Giardia nasalis), where they mature, maturing from L2 to L3 stage, the latter being the stage at which they are ready to be discharged in the feces. SYN: flesh fly.