So here in Illinois we have had a wet spring & summer. The flies and mosquitoes are HORRIBLE! We use the fly predators and increased our allotment but still it’s miserable! So today I bought a 1 gallon tank sprayer, a large bottle of lemon pine sol and a gallon of white vinegar. Mixed it up 1/3 + 1/3 + 1/3 water and sprayed the interior of each stall - NO FLIES! I also sprayed it right on a group of flies that were congregating on some grain & beet pulp “soup” dropped by the 32 yr old toothless wonder - they fell dead! I swept them up with the spilt grain and tossed them out!
Way Cool.