DE is diatomaceous earth. It's a fine powder that looks like talc. It's available in two forms - horticultural and food grade. Food grade is the safest form to use directly on animals (besides the chickens, I've used it successfully on cats, dogs, and ferrets to kill fleas). The food grade DE is available at my local feed store, but only in the 50 lb. sack, for $27 and change. I've seen many threads by BYC folks in various parts of the country that say they have difficulty finding food grade DE. Some have said it is available on eBay and other Internet based businesses, but you'll pay shipping costs. Still worth the investment, IMHO. I cannot testify as to its effectiveness with sticktight fleas since we don't have these horrid things in my part of the country and I've never had to battle them (thank God). There is, however, ample evidence showing that Sevin mixed with Vaseline is effective. The problem remains in the soil. If you do not treat the soil, the sticktights will likely reinfest your flock unless you keep them dusted. DE would be my choice for a preventative measure.