long time ago i knew a guy that would feed fish in his pond by suspending a dead carcass of [insert whatever you've got here] above his pond.  he would put it in a ham stocking (that mesh material hams are placed in during curing and smoking), and hang it from a tree branch over the edge of the pond.  as the flies laid eggs, which then hatched, they would drop into the water feeding his fish.
don't think i would do this in my backyard