author(s)
Nihal R, Suvash Ch. Bala and Anirban Sarkar

abstract
An Experiment was conductedat District seed farm, Bidhan Chandra Krishi Viswavidyalay, Kalyani, Nadia to understand the population fluctuation of two major sucking pest in Bt cotton i.e. cotton aphid and cotton jassid along with correlation with weather factors for consecutive two years during Rabi season 2016-17 and 2017-18. According to two years mean data, aphid population first appeared in the field during 3^rd standard metrological week (SMW) and after the population progressively increased and reached its peak (139.00 aphids per leaf) in 9^th meteorological week whereas Jassid Amrasca biguttula biguttula infestation was first noticed in the field at early vegetative stage of crop i.e. 3^rd meteorological week and remained more or less active throughout the growing season of cotton and reached its peak population (53.10 per 10 leaves) in 8^th meteorological week after that the population showed fluctuating downward and reached the lowest level (8.06/10 leaves) at 20^th standard meteorological week.