I do not recommend calcium or multivitamin dust for frogs, unless you fully understand the chemistry. Calcium will bind with phosphorus, an ingredient found in most multivitamin supplements. As a result, the calcium will not be absorbed, the frog will not benefit. Too much calcium and the frog's metabolism may be affected negatively. If you are going to dust the food items, use calcium only about 2x week if the frogs are adults and 3x week if juveniles.