High light intensity: a critical factor in the wind-tunnel flight of two scarabs, the rose chafer and Japanese beetle.

We analyzed the flight of the rose chafer Macrodactylus subspinosus (F.) (Melolonthinae: Scarabaeidae) and the Japanese beetle Popillia japonica Newman (Rutelinae: Scarabaeidae) in a wind tunnel with controlled humidity, temperature, light, and airflow. The data indicate that an optimum combination of light and temperature dramatically improves their response to lures. Both species took off upwind, oriented to, and contacted the odor source well (40-60%) when light intensity was > 50% of a clear day, temperature was 26-27 degrees C, and relative humidity was 65-75%.