This study aims to monitor the effect of temperature and relative humidity on the population fluctuation of P. tenuivalvata. Ecological studies on population dynamic of P. tenuvalvata (Newstead) (hemipteran: coccidae) on sugarcane fields were studied in Aswan Governorate two successive seasons 2015-2016. Data showed that this pest was active during summer, autumn and winter from May to January). The insect had 3 generations per year. The first generation was observed during May, June and early of July. The second took place during July, August and 2^nd half of September. This generation can be regarded as the most economically important generation. The third generation lasted 3 months i.e. extended from November to the 2^nd week of January. The relationship between insect populations expressed as interval numbers of insects and prevailing weather factors in the two tested years revealed that significant and strong relation between interval of insects and corresponding of maximum and minimum temperature. The correlation coefficient values of the three considered weather factors are (-0.6281, -0.5931 and +0.8612) in 2015 and (+0.6109, +0.5428 and +0.612) 2016 respectively. The effect of one degree of these factors (Unit effect) as indicted by the regression coefficient was about (+.2.95, +3.22 and +3.92) and (-3.68, +2.11 and +3.31) from three factors during 2015 compared to insects in 2016, respectively. The explained variances E.V were calculated (as about 64.35 and 71.2 in 2015 and 2016, respectively. In conclusion, the effect of partial regression as indicated by unit effect was negative for maximum temperature.