Potato tubermoth, Phthorimaea operculella (Zell.) is a serious pest of potato in the fields and country stores in the plateau region of Karnataka and Maharashtra. Studies for determining the rate of multiplication of its population were conducted at 29±1°C and 50±5% relative humidity. Under condition of abundant space and food supply, population of P. operculella on the tubers of potato variety Kufri Chandramukhi increased with an infinitesimal rate (rm) of 0.2439 and finite rate of 1.271 per day. Its population multiplied 121,682 times between two successive generations. Mean time for completing a generation was 19.68 days.
