In 2011, brown marmorated stink bug (BMSB) was first confirmed in Cedar Rapids, Iowa. Since then, live detections have been confirmed in 19 Iowa counties. These stink bugs have been found in and around human structures, mostly homes in urban areas. I don’t know of any BMSB specimens found in field crops.
BMSB have cause severe economic injury to field crops along the East Coast since 2002. This includes injury to corn kernels and soybean seeds. They can also injury many vegetables, fruits, ornamentals, and trees.
I’m setting up a few first detector pheromone traps this summer to see if I can find any near field crops. If you think you found BMSB, send samples to the ISU Plant and Insect Diagnostic Lab.