Get a jump start on fly control. Start your horse on SimpliFly Feed-Thru Fly Control with LarvaStop early in the spring and continue throughout the summer until cold weather restricts fly activity. Break the fly life cycle by preventing the development into mature adults. Prevents development of house and stable flies in manure when horses are continually treated. Highly palatable; just add to horse's feed. Contains no organophosphates. Only equine feed-thru fly control granted reduced-risk pesticide status by the EPA. Contains Diflubenzuron.