Technical Abstract: The purpose of this study was to develop and evaluate lures for adult green June beetles, Cotinis nitida (L.), for future use in a mass trapping program. Volatile organic compounds collected from head space of green June beetles feeding on fermenting ripe apple, the natural lure that elicits feeding aggregations, were identified and confirmed by gas chromatography and mass spectrometry. Yellow funnel traps baited with 91% isopropanol or the five component TRE blend were equally effective in eliciting aggregation behavior and often more attractive to green June beetles than the natural lure. In 2008, three trap lines adjacent and parallel to the perimeter of two vineyards, each with 12 Xpando yellow funnel traps baited with either 91% isopropanol or the TRE blend, differed in catch of green June beetles across sample dates, and sample date by bait interaction but there were no differences among these two baits. A season total of 324,007 green June beetle were captured by these 36 baited traps. A brief review is included of fermentation volatiles attractive to insects. We conclude with the potential cost to use the mass trapping against adult green June beetles.