Identification, Images, & Information
For Insects, Spiders & Their Kin
For the United States & Canada
[cite:873469]
NB: data published in several more recent papers not reflected
see also(1)(2)
http://museum.unl.edu/research/entomology/Guide/Scarabaeoidea/Scarabaeidae/Aphodiinae/Aphodiinae-Overview/AphodiinaeO.html

New link
http://unsm-ento.unl.edu/Guide/Scarabaeoidea/Scarabaeidae/Aphodiinae/Aphodiinae-Overview/AphodiinaeO.html