The influence of temperature, relative humidity and diet composition in the duration and velocity of the development cicle of Gnathoccnis comutus Fab., was studied. Each of two diets (Aand Bl was tried in presence of 5 different combinations of temperature and humidity. Optimal conditions fOI development were found to be: 28°C and 85-90% R.H.. in which the complete cycle lasts 54 days. the larval stage is the critical one in the development in which a htgh variation among individuals in both, velocity and span of development, are notorious. The cycle duration is virtually the same for both diets, but in the diet A. a better adaptability, expressed as a proportion of descendents, was observed. Life tables and surviving curves were made.