Mites are a common parasite with wild caught frogs and toads. Treating mites is quite easy. You can open a tetracycline capsule (for treatment of tropical fish) and pour powder in a 1/4 cup of distilled water, mix thoroughly. Place a couple of drops on the toads belly. Refrigerate unused portion. Retreat procedure 24 hours later. Before applying to toad, make sure the solution is at room temperature. Discard after second application. This should get rid of the mites. Clean and sterilize the terrarium, furniture and replace substrate.