If you pick up any horse rag you should see adverts placed by Arbico or
Spalding Labs. They are the breeders of these little critters and will
mail them directly to you, and will recommend a certain dose every three
or four weeks depending on number of animals. They also do nematodes.
Have used both sources in the past and found Arbico to be about half the
price of Spalding. I order once at the begining of the season and
receive deliveries for the rest of the season.
-- Nicco Murphy, San Diego County