 More recently, it has been suspected that the western cicada killer represents more than one species. It co-occurs with the eastern cicada killer (S. speciosus) and Pacific cicada killer (S. convallis) at Big Bend National Park in Texas. There the three wasps hunt and nest in the same locales, and the eastern and western cicada killers hunt the same cicada species. Analysis of mitochondrial DNA showed that the western cicada killer contains two divergent clades, which may represent distinct species. The two clades appeared to be split by the Rocky Mountains, with one occurring mainly to the south and east, the other to the west.
