The biting habits of Leptoconops bequaerti. II. Effect of meteorological conditions on biting activity; 24 hour and seasonal cycles.
The following is based largely on the authors' summary. Some of the factors that contribute to changes in the biting rate of L. becquaerti with time (daily and seasonal cycles of activity and the influence of meteorological conditions) were investigated 'by using data obtained from the catches described above but with the regular weekly catches extended until February 1961. L. becquaerti was found to be diurnal, biting from dawn until sunset, with maximum activity between 8 and 9 a, m. and another less intense spell of biting in the late afternoon. Adults were present throughout the year, with periods of peak abundance in August and February and low numbers in May-June and December. This seasonal biting cycle is probably related to rainfall, which is highest in May-June and September-November. The biting rate was less affected by meteorological conditions than that of any other Ceratopogonid studied sotar [cf. 47 12; 52 26, 144]. Females bit freely in the open at wind speeds of 10-12 miles per hr. but disappeared when the speed reached 15 miles per hr. Wind speed had more influence on biting rate than temperature or illumination, but the inhibiting effect of high wind was masked by the positive stimuli provided by high temperature and light intensity. Saturation deficit had no effect. After data had been standardised in relation to wind speed, temperature and illumination by the application of partial regression coefficients, there was no evidence of a change in biting rate during the period over which weekly observations were made, nor was there any correlation with phases of the moon and therefore with tidal range.