Well, it is supposed to kill the bugs...I personally use SEVIN and mix it with the DE and garden dirt and wood ash. They can dust bathe whenever they want. Unfortunately mine do not all do this! I just brought in a very large EE roo that is finally getting better from his mite infestation. I cant find any others in the flock (so far) that have mites...there must be at least one other though! I believe that when you free range your birds they have the chance to pick up anything and everything! I mean the wild birds are always all around...if you have an infestation you probably need to get it under control before you can use the preventative stuff. Terri O