Diurnal periodicity of fight in some Delphacidae and Cicadellidae associated with rice

Abstract. 1. The diurnal periodicity of flight of delphacids and cicadellids associated with rice was assessed by suction trapping.
2. All the delphacids examined and most cicadellids showed a bimodal, crepuscular pattern of flight, the major peak occurring in the evening.
3. Some cicadellids showed a unimodal crepuscular pattern of flight activity with the peak occurring in the evening, whereas flight activity of Cofana spectra and Cunimaculata continued throughout the night.
4. Changes in the periodicity of flight activity of Nilaparvata lugens, Sogatella furcifera, Recilia dorsalis and Macrosteles striifrons were observed in relation to phases of the moon and the nature of the habitat.
5. Periodicity of take-off for N.lugens, Sfurcifera and R.dorsalis assessed by canopy net traps also showed a bimodal, crepuscular pattern with the major peak occurring in the evening.
6. The significance of diurnal periodicity is discussed in relation to the flight behaviour of the insects studied.