We investigated the performance of larvae of the invasive maize, Zea mays L., pest Diabrotica virgifera virgifera LeConte (western corn rootworm) on roots of alternative host plants. During laboratory feeding trials, we measured growth and amount of ingested food and determined the food conversion efficiency of second instars. We tested eight species of weeds (seven monocots and one dicot) and three monocot crops with regard to host plant suitability by using a newly established method. We additionally examined the carbon/nitrogen ratio and the phytosterol content of the different plant species as parameters to interpret larval performance. Larval growth, the amount of ingested food, and the food conversion efficiency differed significantly between plant species. Plant species with a high nitrogen content were less suitable for D. v. virgifera development. The phytosterol content had a significant influence on the amount of ingested food, but not on larval weight gain. The performance of D. v. virgifera larvae on alternative hosts was comparable with their performance on maize. The ability to use alternative hosts for larval development may contribute to the invasion potential of D. v. virgifera and has important implications for integrated pest management.