The expanding demand for biofuel feedstock may lead to large-scale conscription of land for monoculture production of biofuel crops with concomitant substantial negative impacts on biodiversity. We compared moth diversity in light-trap samples from corn, miscanthus, switchgrass and native prairie, to determine whether there is an observable relationship between plant species diversity and moth abundance and diversity. Moth alpha diversity was highest in prairie and was higher in switchgrass than in the other two biofuel crops. Beta diversity generally was low among the biofuel crops, and prairie shared lower beta diversity with switchgrass than with corn or miscanthus. Analysis of variance showed no significant differences in moth abundance per species among treatments. The alpha and beta diversity index findings are consistent with those of other studies on arthropods in biofuel crops and provide evidence to suggest that large-scale conversion of acreage to biofuel crops may have substantial negative effects on arthropod biodiversity both within the cropping systems and in the surrounding landscape.