DE is awesome !
We have had fantastic success with DE flour we buy at our Cenex feed store, ask your feed store to order it for you and chances are it will come in on their next shipment and you can just go pick it up.
I get DE 'flour' called food grade, for 80# it was about $25.
We make 25X25" boxes with plywood bottom and 10" high sides and add 1 sack of play sand from your home center (like Home Depot) or any clean and dry sand, add about 6 to 8 cups of the DE flour, and 1 or 2 cups pultry and vegetable dust (permethrin) and mix, keep in a dry place and your hens will love to dust bathe in it and kills all louse and mites !
A little dusting mixed in their feed and kills all worms !
Fair warning though, it is dusty, and the birds can creat a fog cloud to the point where they run around looking as if they are on fire.
Make sure you keep heat lamps and heaters clean of this flyaway dust.
It isn't the best thing to breath as it is silica, so you need a place for the dust bed that has some ventilation.
The resulting flyaway dust kills all insects that may be lurking in the henhouse, or where ever the dust lands~
And it is great in the garden !