To know the initial occurrence and subsequent build-up of aphids population on chilli crop in relation to weather parameters, the field experiments were carried out from 2010-2012 at Horticultural Research station, Lam, Guntur, Andhra Pradesh. Seasonal incidence of aphids was recorded from leaves and fruits at weekly intervals during the crop growth period. Based on the two years data, the results revealed that the infestation and severity of aphid population were highly influenced by weather parameters. In 2010-11, aphid incidence was initiated from 42 th STW week (1.51/leaf) and it continued up to the harvest of the crop 9 th STW(1.25) with a peak activity at 50 th STW (46.72). Correlation coefficients worked out between aphids population and weather parameters of preceding one week indicated that among the various weather parameters, significant positive correlation was observed between morning relative humidity (0.08**), evening relative humidity (0.53*) and minimum temperature (0.66**) whereas negative significant correlation was observed with maximum temperature (-0.24**) and rainy fall (-0.55**) with aphids population. Similar trend was observed at preceding two weeks weather parameters and aphids population in same year of study. Significant positive correlation was observed between morning relative humidity (0.01**), evening relative humidity (0.57*) and minimum temperature (0.68**) whereas negative significant correlation was observed with maximum temperature (-0.25**) and rainy fall (-0.56**) with aphids population. About 2011-12, incidence was initiated from 44 th STW (2.79) and it continued up to the harvest of the crop 4 th STW (3.42) with a peak activity during 1 st STW (13.64) Correlation coefficients worked out between aphids population and weather parameters of preceding one week indicated that among the various weather parameters significant positive correlation was observed between weather parameters of morning relative humidity (0.46**), evening relative humidity (0.51*) and minimum temperature (0.36**) whereas negative significant correlation was observed with maximum temperature (-0.63**) and rainy fall (-0.36**) with aphids population. There was a similar trend in preceding two weeks weather data correlations with. Weather parameters of preceding two weeks indicated that among the various weather parameters significant positive correlation was observed between weather parameters of morning relative humidity (0.48**), evening relative humidity (0.47*) and minimum temperature (0.24**) whereas negative significant correlation was observed with maximum temperature (-0.62**) and rainy fall (0.32**) with aphids population. The combined effect of weather parameters on incidence of aphids was worked out; it showed that the variation in the incidence (62 to 74%) was contributed by the weather parameters.