Many will tell you this too...it's no proof.So many on here will tell you not to use FGDE, but I have used it for 4 years and have yet to have a mite infestation.
I don't use it and have not had mites.
I've read a lot of stories about DE use as a preventative and then a mite infestation happens anyway.
Sorry, serious pet peeve about this type of misinformation.