Abstract
Observation of nocturnal flight activity of Culex tritaeniorhynchus was carried out by means of hourly collection in a light trap and the dissection of the females. The diurnal changes of C. tritaeniorhynchus showed a bimodal pattern and the height of two peaks fluctuated regularly according to population trend. When numbers caught through the night increased, numbers in the first peak increased remarkable but those in the second peak slightly. The proportion of numbers in the first peak for numbers caught through the night increased to almost 90%. The parous rate at 19-20hrs. was lower than that at 03-04hrs, and in parous females caught at 03-04hrs. there were many individuals that the condition of the connecting stalk of follicle showed sac like. These observations suggest that the age-composition fluctuates through the night in nocturnal flight activity of female population.
