Volunteer potato is very difficult to control in potato crop rotations. We are exploring the ability of Colorado potato beetle (CPB) to suppress this weed and other Solanaceous weeds. The purpose of this study is to quantify the interactions of herbicide dose and herbivore load on weed fitness. The results would identify the extent to which herbicide use could be reduced for a range of beetle densities, while maintaining weed suppression. The use of CPB in combination with a range of prometryn doses is proving more effective in eliminating volunteer potato above ground biomass (AGB) than the use of either alone. Preliminary analysis indicates complete skeletonization occurred by the 14 day post spray harvest endpoint when using 40 first instar larvae. Beetle levels of five and ten first instar larvae were also analyzed but produced inconsistent results due to possible light quality issues that would affect the mode of action of a photosystem II inhibitor such as prometryn (this problem has been resolved). This work is currently ongoing.