Here’s the old maps (from C.L. Marlatt’s The Periodical Cicada from 1907) for Brood III or Brood XIX. Brood III is a 17-year Magicicada due to emerge in 2014, and Brood XIX is a 13-year Magicicada due to emerge in 2011. It looks like stragglers (periodical cicadas emerging years in advance of when they’re supposed to emerge) in Iowa would be Brood III, and those emerging in Missouri are probably Brood XIX, and possibly Brood III in the north of Missouri. If you find some, take photos, video of their song, etc.