The features of the seasonal activity of bumblebees (Bombus distinguendus, B. pascuorum, B. bohemicus, B. flavidus, B. sylvestris, B. hypnorum, B. jonellus, B. sporadicus, B. lucorum, B. sichelii) of the Middle Ob lowlands are studied. The total abundance of bumblebees during the flight period depends on the sum of effective temperatures in the spring months (the correlation coefficient is 0,99 (p=0,05)). The total abundance of bumblebees is less dependent on the sum of effective temperatures in the spring-summer-autumn months (the correlation coefficient is 0,50 (p=0,05)).