抄録
The relation between the growth of the larva of the almond moth, Ephestia cautella, and its population density was obtained by measuring the width of head capsule of the larvae which were reared under the constant environmental condition of 30°C and 70 per cent relative humidity with the rice bran as food of larvae.
Most of the larvae which were reared under low density had five instars, whereas some of these reared under high density had more than five instars. As the density increases the larvae which have six or more instars becomes high in proportion in the population.
DYAR'S law and TOKUNAGA'S formula of insect growth are not applicable to either cases.
The head width of the larva becomes narrow with increasing the larval density. But the percentage of decrease of head width in the high density (400 eggs in 5 grams of rice bran) to that of the low density (25 eggs in 20 grams of rice bran) is not so great as compared with these in that of the adult. The percentages are 0.7 per cent in the 2nd instar, 4.8 per cent in the 3rd instar, 4.7 per cent in the final instar of larvae, and 14.5 per cent in the male moth and 14.7 per cent in the female moth.
Under low density the duration of each developmental stage in days is as follows: Egg 3.0; 1st instar 3.5; 2nd instar 2.2; 3rd instar 2.8; 4th instar 3.4; 5th instar 5.9; pupa 6.8, total about 28 days. With increasing density of larvae the duration of each larval stage is prolonged, especially in the final instar, while that of the pupal stage is scarcely affected.
