Here's a short Video clip of the Quail Taking a Dust Bath in Mass in a pan filled with food grade diatomaceous earth and ground clay sand .
You specifically said "food grade" diatomaceous earth. Some people think that means you need to go to the health food store and pay a premium for it. Diatomaceous Earth is used extensively in the worming of goats and other livestock and is available much much cheaper at the feed store. I don't know where you're getting yours, I just didn't want anyone spending a lot more than they would need to.
I was thinking I'd plan a weekend to go hunt with you sometime this season, now I'll know to watch my back so as not to get powdered! lol
I am unfamiliar with the Regular DE (grey). The white stuff is what I use and yeah it's called "food grade" too, but I only pay maybe $15 for a 50lb bag whereas it's about a dollar a pound at the health food store.
I use a light dusting of DE in everthing I feed from the goats to the hunting dogs. Partly because it helps keep parasite levels in check, but also because it keeps bugs out of the feed. I've found this particularly true with keeping ants out of the dog food!
I have dusted hawks with it, but have had better success with a pyrethrin type mite spray.
That's something I had thought about doing at one time. A friend of mine has the brooder set up and it's a four level type cages. It's designed for the quail to lay the eggs and then take the eggs and put them into a incubator. Would be nice if a person had a small building in the country where you could put several pairs together and them place the young on screen wire for health purposes.