They sell Diatomaceous Earth at Tractor Supply because people buy it as a feed supplement for beef, goats, sheep, chickens, quail, ducks, hamsters, guinea pigs, rabbits, etc. It is also reported to help keep intestinal worms at bay. It is also used as a dust to keep fleas and flies down either on the animals or in their bedding areas. I have also purchased the 'food grade' DE as a powder just like flour which is easy to dust onto plant foliage.
