Moths are often specialists of particular host plants, making them good indicators of what plants are present in a habitat, as well as the overall health and diversity of an ecosystem. Moths are important pollinators, and their caterpillars are an important food source for many species of birds. The objective of this study was to compare the abundance, species richness, and structure of moth assemblages in planted tallgrass prairies and oak hickory forests in Decorah, Iowa. During the summer of 2018, black light bucket traps were set up in three planted prairies and three oak-hickory forests on five nights from early June to mid-September. Moth samples were brought back to the lab, frozen, then sorted and counted. Representatives of each species of moth were pinned, spread, and identified to species. We collected a total of 12,290 moths, representing 468 species and 34 families. There were significantly more moths, families of moths, and moth species in the forests than in the prairies. Among sample dates over the course of the summer, there were no significant differences in either number of moths or species richness. This study provides valuable baseline data for monitoring future changes in moth diversity and abundance in Northeast Iowa.