The fatal viral illness known as epizootic hemorrhagic disease (EHD) is transmitted to whitetails by biting midges. The host deer bleeds to death internally. EHD runs in cycles, and in areas where it occurs frequently, deer can build up a resistance to it, but no one is sure exactly how or where the virus originates. In late September of last year, the Iowa Department of Natural Resources declared, "EHD is killing our deer." By that November, several of my hunting group had begun bowhunting on a property we share, and it seemed as if the whitetail numbers had been cut in half.