Nosema bombycis infected moths of the two silkworm races, viz., NB4D2 (a bivoltine) and PM (a multivoltine), generated by inoculation of larvae immediately after IV moult with a spore load of 105 spores /ml were preserved at 4 different temperatures, viz., 10°C 26°C 28°C and 32°C, in incubators under 60-70% R.H. Under each temperature, they were preserved for varying durations viz., 24h 48h 72h and 96h and the rate of spore multiplication was assessed. Analysis of spore concentration and comparison of the spore yield was made between the temperatures.  The results indicated that with increasing temperature, in both races, significant increase in the number of the spores were observed. With increase in duration of preservation, the effect was markedly pronounced.  It could therefore be presumed that a low level of infection of Nosema bombycis at the time of emergence of moths can be accelerated if the moths are preserved for a few days before conducting microscopic examination.    If the preservation is done at 28°C-32°C it has an added advantage of further enhancing the multiplication.  The observations tend to indicate that the detection efficiency of Nosema bombycis infection in silk moths appreciably increases if the moths, before microscopic examination are preserved for four days at a moderately higher temperature of 28°C -32°C. The results could become handy in effective diagnosis of Pebrine at seed production levels.