There are three formulations of terramycin (TM) registered for use on honey bees for prevention of American Foulbrood (AFB), a bacterial disease that can kill the colony. None of these formulations may be used when honey is being produced for human consumption. TM25 is a water soluble mixture that comes in a 6.4 oz. package and contains 25 grams of active ingredient (a.i.), oxytetracycline HCL, per pound. There are 10 grams (10,000 mg.) of a. i. in each 6.4 oz package. TM50D is not water soluble, comes in a 50 lb. bag. and contains 50 grams (50,000 mg.) of a. i. per pound. TM50D must be diluted with powdered sugar before it can be used in extender patties or as a dust treatment. A third formulation, TM100D, is rarely used by beekeepers and is not included in the following calculations. Terramycin can be applied to honey bee colonies using three methods: in extender patties, as a dust and in liquid feed.
"SP596-Using Terramycin for the Prevention of American Foulbrood," The University of Tennessee Agricultural Extension Service, SP596-2.5M-1/02 E12-4615-00-017-02, https://trace.tennessee.edu/utk_agexdise/5