I read somewhere of a fellow obtaing a medium animal carcass,and hanging it over their favorite fishing spot,in this case he stung a rope across a pond and suspended the carcass oabove the water in the middle of the pond.After a few days of heat,the flys having layer eggs,hatched and began dropping maggots into the waiting mouths below.
I imagine one would need to position himself to avoid the small,but Dan,I bet I would work,but it's easier to buy them nowadays