1. Department of Natural Resources and Environmental Sciences, University of Illinois, 1102 S Goodwin Avenue, Urbana, Illinois 61801, USA
2. Illinois Natural History Survey, Prairie Research Institute, 1816 S Oak Street, Champaign, Illinois 61820, USA
3. College of Veterinary Medicine, University of Illinois, 2001 S Lincoln Avenue, Urbana, Illinois 61820, USA
4. Animal Parasitic Diseases Laboratory, Beltsville Agricultural Research Center, Agricultural Research Service, US Department of Agriculture, 10300 Baltimore Avenue, Beltsville, Maryland 20705, USA