Studies on the innate capacity for increase of Plutella xylostella (L.) was carried out under laboratory condition at a constant temperature of  25 + 10C on cabbage during the year 2005-06. The maximum duration of egg, larva and pupa were observed as 3, 14 and 5 days, respectively. The net reproductive rate (Ro) of  95.33 was obtained with a mean length of generation (T) 27.45 days. The intrinsic rate of natural increase in numbers (rm) was 0.1635 females per female per day and the population was multiplied 3.1963 times per week. On reaching the stable age distribution the eggs, larvae, pupae and adults contributed to the tune of 56.86, 37.71, 4.27 and 1.44 per cent, respectively. The expected further life at the age of 15 to 20 days was reduced to 7.08 from 12.82 days.