I had a phroid outbreak in my blaberus bin. I changed out the substrate, let it dry out, flypaper, vinagar traps, and extra springtails. Nothing was working, they were starting to spread into my other bins and gecko tanks. As a last resort I added buffalo beetles(lesser mealworm) they helped but did not solve it. I noticed my oriantalis bin has a Vaseline barrier, there were flys stuck to it. I slathered vaseline all over the top and sides of the blaberus bin and within a few days they were all gone. IMO a vaseline barrier is the best offense for a fly problem