Field-based trapping experiments were conducted in Ohio in 2003, 2004, and 2008 to determine the influence of (—)-α-pinene on the attraction of exotic and native ambrosia beetles (Coleoptera: Curculionidae: Scolytinae) to ethanol-baited traps. In 2003 and 2004, we determined the effect of adding an (—)-α-pinene ultrahigh release lure (UHR; 2 g/d at 20°C) to traps baited with an ethanol UHR lure (0.39 g/d). Fewer Anisandrus (Xyleborus) sayi (Hopkins) and Xyleborinus saxeseni (Ratzeburg) were collected in 2003 and 2004 from traps baited with ethanol UHR plus (—)-α-pinene UHR compared with ethanol UHR. (—)-α-Pinene also reduced the attraction of Xyloterinus politus (Say) to ethanol-baited traps in 2004. Total captures of Xylosandrus germanus (Blandford) in 2003 were higher in traps baited with ethanol UHR plus (—) -α-pinene UHR than in traps with ethanol UHR alone but not in 2004. In 2008, captures were compared among traps baited with eight combinations of ethanol and (—)-α-pinene at both UHR and low release (LR) rates. Release rates for ethanol LR and (—)-α-pinene LR were 0.027 and 0.0015g/d, respectively. (—)-α-Pinene UHR and (—)-α-pinene LR reduced the attractiveness of ethanol UHR to A. sayi and X. saxeseni. Ethanol UHR was also more attractive than ethanol LR to A. sayi and X. germanus. These findings demonstrate traps baited with ethanol alone are more effective than ethanol plus (—) -α-pinene for monitoring ambrosia beetle flight activity in ornamental nurseries. Ethanol release rate is also an important consideration for monitoring purposes.