The most recent discovery of Japanese beetles in the state of Iowa started in 1994 in Scott County. Since then, Extension staff, landscapers and citizens have sent samples and digital images confirming the presence of this pest in 37 counties. See the map below. If you find Japanese beetles in a county not marked on the map, please let us know by sending specimens or digital images including capture location and date. Mail to: 104 Insectary, ISU, Ames IA 50011. Email to: email@example.com Reported Distribution of Japanese Beetle in Iowa, 1994 - 2008.