I was driving in sioux falls one day in probably july or august, stop at a red light and a side dump turns in from of me. Black cloud spewing out the top, i thought it was on fire. Nope, swarm of flies so thick it would block out the sun. It was the gut truck coming out of the hog plant. I had to pull off until the smell went away. I was going to get something for lunch, decided i didnt feel like eating anymore.