The diel flight activity in Cathartus quadricollis (Guerin-Meneville) (Coleoptera: Silvanidae), a predator of two important pests in Hawaii, coffee berry borer, Hypothenemus hampei (Ferrari) and tropical nut borer, Hypothenemus obscurus (F.) (Coleoptera: Curculionidae: Scolytinae) was studied in a macadamia nut orchard using yellow sticky traps baited with pheromone and fungal volatile attractants. The study was conducted at different months throughout the year and at different times during the lunar cycle (new moon and full moon). Flight activity peaked in the late hours of the photophase into the early hours of the scotophase, between 1830 and 2000 h; flight activity also occurred but to a lesser extent in the early morning hours between 0700 and 1030 h. Numbers of captured C. quadricollis during periods of flight activity were negatively correlated with wind speed. The implications of these findings for the development of optimal pest management strategies including biological control are discussed.