The fluctuation of adult emergence at regular intervals was observed, when the population of the almond moth, Ephestia cautella, was bred under a constant physical environment with the periodical supply of rice-bran (TAKAHASHI, 1953).<br>In this experiment, the influence of the time interval of food supply upon the mode of adult emergence was examined. Four populations were bred with the food supplied at intervals of 10 days (Populations A and B), 20 days (Population C), and 40 days (Population D), respectively, under the constant environmental condition.<br>In Populations A and B, the peak of emergence occurred periodically at intervals of about 35 days. This fluctuation might be caused by the periodical occurrence of the destruction of the individuals by the direct interaction among individuals of di f-ferent ages (TAKAHASHI, 1959b), especially by the larval cannibalism to the eggs and the pupae. The length of a period of this fluctuation coincided with the length of the life cycle, so this fluctuation can be interpreted as the sequence of emergence in a population in each generation. Therefore, the repeated introduction of eggs at the starting point of the experiment and the frequent supply of food at a short interval would not build up a stationary age distribution. But, when the length of interval of food supply was longer than the length of the life cycle of an insect, the shortage of food occurred before the next food supply, so the fluctuation of adult emergence corresponded to this longer interval of food supply, as was seen in Population D.<br>When the population in each generation was computed from the number of emergent adults as mentioned above, it maintained a steady state from the second generation in Populations A and B. The population trend of Poplation C was similar to those of Populations A and B, excepting an overshooting growth of population in the second generation. In Population D, the population fluctuated violently.<br>The reproduction curves drawn from the census data of the four populations were different in their shapes. The curves of Populations A and B were the saturation type, while Population C took the mountain shaped curve. In Population D, the points represent the relation to the reproduction curve, but they were not distintinct. They rather seem to be the mountain shaped curve. These differences might be due to the different modes of population regulation among the four populations as mentioned above.