The purpose of the model for predicting the incidence and development of tobacco thrips is to determine the critical periods for the control of this tobacco pest and the trends in the development of thrips populations for a given period of time. The model essentially provides a possibility for continuous monitoring of tobacco thrips numbers depending on biotic and abiotic factors. The most decisive of these factors are the average daily temperature and relative air humidity and the relative population density during the current and the preceding period. The model is based on the indirect methods for prognostication and signalization and chiefly on the temperature-and-humidity characteristics on which tobacco thrips is directly dependent. The model serves to define approximately the right timing of control measures against tobacco thrips and TSWV, respectively, thus ensuring the most correct application of a rational up-to-date system for predicting the threat to tobacco by the most important pest - Thrips tabaci Lind.