Diel flight periodicities of some Dytiscidae (Coleoptera) associated with California rice paddies

Diel flight periodicities of Eretes sticticus (L.), Hygrotus medialis (LeConte), Laccophilus mexicanus atristernalis Crotch, Liodessus affinis (Say) and Thermonectus basillaris (Harris) were monitored with a rotary net machine and a black light trap. All were affected to some extent by air temperature, light intensity, and wind velocity. Most flights occur at temperatures of 23–24°C when there is no wind. Flights appear to be limited by temperatures as low as 16°C and as high as 32°C, and variously by wind velocities of 8 kph or more. The relative size and the geographical range of each species may influence its period of peak flight. Larger species tended to initiate flights later in the evening, and had a longer period during which peak flight could occur.