Kathy, stick with what you're using. It's a sales persons job to sell their product and will say anything to get you to buy their product. Anyone that tells me that DE is an effective wormer or even hints at it being an effective wormer...it's time to walk the other way. Safeguard and valbazen are very safe wormers and arnt expensive and have up to 3 year expiration dates...more bang for the buck. Safeguard kills all worms except tapeworms, Valbazen kills all known worms that chickens can get including flukes. We have hundreds of BYC'ers that can verify the effectiveness of these wormers.