Cotton is an important crop for the Pakistan and in the globe too. Thus, to access the availability of biological fauna over a year, a study was designed. The study was carried out Research Farm of MNS-University of Agriculture, Multan, Department of Entomology, Faculty of Agriculture & Environmental Sciences during 2018. In the study, population of beneficial insects was corelated with the weather parameters (temperature, humidity and rainfall on two cotton genotypes; Bt (MNH-992) and Non-Bt (Cyto-124). The four natural enemies i.e. ladybird beetle, green lace wing, syrphid fly and spider were studied. The population of the natural enemies remained active throughout the studied period. The population of green lace wing and ladybird beetle were maximum in June to September, respectively. The study showed that green lace wing and ladybird beetle showed positive correlation with temperature while negative with rainfall. While, spider’s population showed negative correlation with all-weather parameters except sunshine hours. The population of spider was maximum in last week of September while disappeared in the last week of October. The study revealed that the natural enemies were observed rarely in month of May, early stage of crop. The study resulted that weather parameters like temperature, humidity and rainfall play significant role in fluctuation of natural enemies.