author(s)
Suvash Ch Bala, Nihal R 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 whitefly and cotton thrips along with correlation with weather factors for consecutive two years during Rabi season 2016-17 and 2017-18. According to two years mean data, whitefly infestation was first recorded in 3^rd standard meteorological week (SMW) of the crop and continued up to 15^th SMW. However, it reached its peak population in 13^th SMW with a population 41.30 per 5 leaves. The thrips population first commenced at 7^th standard meteorological week, maximum population (160.0 thrips per leaf) was recorded on 14^th SMW and least population (2.30 thrips/leaf) was recorded on 20^th SMW. Among the weather factors maximum temperature showed positive correlation whitefly, Bemisia. tabaci and thrips, Scirtothrips dorsalis population the rainfall is favorable the activity of whitefly whereas the thrips were unaffected by rainfall.