First, watching a runner duck run is awesome. They can find their own food. They aren't like pekins in water. Mine haven't started laying but I heard their decent.
I have 25 Cornish Rock and 9 Rhode Island Reds. What are some methods of fly control? This is more of an issue with the cornish rock than the the Reds?
Since the Reds do not eat or drink as much as the broilers they produce less wet manure = fewer flies. Of course the Reds will take months and months (as well as many more pounds of feed) to get to useable weights.
Keep the litter under the broilers dry by eliminating water waste, providing ventilation, and turning, replacing or adding to the litter.
Thanks for the response. My reds are for eggs only, but my rocks are for eating. I purchased some pine shavings and I am combining those with hay for the litter.