A few years back I accidentally attracted this fly,when one of my corn buckets got wet and I went on vacation. My buddy in charge of feed the chickens decided to throw it all in the compost bin which had nothing leaves and grass clipings. When I returned from vacation we had a fowl smell in the compost bin.
With some research I found out what they were and how fast they ate any decaying fruit and veggies.
So now I have free high protein fish food, also good for poultry and reptiles.