I am a small-scale backyard flock owner and currently have just three hens. Only one has nits on her feather shafts but two weeks ago today we treated all three using the dawn soap bath/vinegar bath and applied DE to the birds and there yard/coop. Today I still see nits but not lice on the one same bird. But now the nits can be pulled off the shafts where as before I couldnt break them off the feather. I plan to reapply the DE tomorrow but are they going to go away? Can I introduce new birds yet?