Uric acid content and xanthine dehydrogenase activity were measured using translucent silkworms (od, oew, og, ok) and their normal segregants. The results obtained were as follows:
1. The amount of uric acid of the integument in translucent mutants was markedly less than in each normal segregant. On the contrary, faeces and haemolymph of translucent larvae contained a great amount of uric acid as compared with those of normal segregants without exception.
2. In og segregant, xanthine dehydrogenase activity of the fat body was higher in normal segregant than in translucent mutant, from the second day of the last instar to the matured stage. However, there was no clear difference in xanthine dehydrogenase activity between od and ok segregants.
3. Little or no xanthine dehydrogenase activity could be detected in the integument in all translucent and normal silkworms.
4. In view of results obtained and unpublished data as to uricase activity of the integument, it may be suggested that the great difference in the content of uric acid of the integument between translucent and normal silkworms is not resulted from the difference in the xanthine dehydrogenase activity, but is due to the difference in adsorption and reservation of uric acid in epidermal cells.

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The European red mite, Panonychus ulmi (KOCH), has become one of the most serious pests in the apple orchards in Aomori Prefecture since 1950. It is very important to find the initial date of hatch of winter eggs from the economical standpoint. In the present paper, therefore, attempts were made to determine the total effective and the lower limit temperatures for the development of winter eggs based on data during the period 1951-1960 except 1953. The relations between the initial date of hatch from winter eggs and the climatic conditions or the state of growth of some apple varieties were also analyzed. The results are as follows:
1. It is proved that the total effective temperature of 195.4 day-degrees C was required to complete the development of winter eggs and that a temperature of about 7°C was the developmental zero.
2. It is found that there is high correlation between the initial date of hatch and the total temperature during the period from March to April 25th, 30th and May 1st of the said nine years.
3. As a result of examining the relation between climatic conditions and the initial dates of hatch, there was a high inverse correlation with the temperature of April. In order to forecast the first day of hatch following formulae seem to be applicable.
y=-2.910x+27.983 (y: Initial date of hatch x: Average temperature at 9 a.m. in April)
y=-2.348x+8.322 (y: Initial date of hatch x: Minimum temperature in April)
y=-3.507+50.030(y: Initial date of hatch x: Maximum temperature in April)
4. A high correlation was ascertained between the initial date of hatch and the growing state of apples. Examining the relation with the principal varieties of apple in Aomori Prefecture, the forecasting formulae of the initial date of hatch are as follows:
5. It was required about 10 days to complete the hatching of 99 per cent of the winter eggs in 1959 and 1960. The termination of hatch is considered to lie between the each initial date of blooming of Jonathan and Ralls Janet. It can be said that the time just before blooming of apples is best for control in early stage of the European red mite.

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The effects of the population density and food plant during the larval period on the determination of the wing-form (macropterous and brachypterous forms), and the appearance of the diapausing egg and the host plant preference have been studied with the white back planthopper, Sogata furcifera HORVÁTH. The results are summarized as follows:
(1) In Hiroshima Prefecture the macropterous males and females of the white back planthopper appear in the paddy fields from late June to early July for the first time. Then the brachypterous females appear and increase in number during the summer. In late August and early September the macropterous forms disappear from the paddy fields. They pass two generations during the summer in the paddy fields.
The wing-form of adult is determined by the environmental factors affecting during the larval period. All of the emerged adults grew the macropterous form when the larvae were reared under high population densities and fed on the weeds (Poa annua L. and Alopeculus platensis L.).
(2) It was found that the adult showed distinct host preference. From late June to early July, the planthoppers appear in the paddy fields, and oviposit more on the rice plant (Oryza sativa L.) than on the weed (Poa annua L.).
(3) The planthoppers disappear from the paddy fields from late August to early September. Just about this time, they oviposit more on the weed (Panicum crusgalli L. var. submutica MEY.) than on the rice plant.
(4) The planthoppers which were reared on the weed (Panicum crusgalli L. var. submutica MEY.) did not oviposit on the rice plant at all, but oviposit on the weeds such as Poa annua L. and Alopeculus platensis L.
(5) When the larvae were reared with leaf or sheath of the weed (Panicum crusgalli L. var. submutica MEY.) during October and November, the emerged adults oviposited the diapausing eggs. But the adults which were reared with rice seedlings or sheath of rice plant being after heading never oviposited the diapausing eggs. The diapansed eggs did not die under the low temperature of -4°C for 24 hours and overwintered in the egg stage.
(6) The diapaused eggs which have overwintered grow active in the middle of March and their hatching begins in the middle of April. The newly hatched larvae take the weed (Poa annua L.) for food plant and emerge late in May. This is the adult of the first generation of that year. The planthoppers which appear in the paddy fields from late June to early July are the adults of the second generation.

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In a series of papers concerning the effect of fertilizers applied to the rice plant on the growth of the rice stem borer larvae, the authors have demonstrated that good growth of larvae can be attained by feeding rice plant cultured on soils or in solutions rich in nitrogen, while phosphorus fertilizers usually had no significant effect.
The present experiments were undertaken to know whether or not the growth of larvae is affected by application of potassium fertilizers to the rice plant. Three experimental series were provided for rearing the larvae, as follows:
Series 1: Larvae were reared on living rice plants grown in a greenhouse on soil supplied with potassium fertilizer, at high, low, or zero level.
Series 2: Larvae were reared on living rice plants cultured in a greenhouse in nutrient solution containing potassium at high or low level.
Series 3: Larvae were reared on steam-sterilized rice plant stems, in flask, at 28°C, under an aseptic condition; the plants used having been grown in nutrient solution in the same manner as in the series 2.
As is shown in the following table, there was found, within each series, practically no difference in the growth of larvae.
Contents of several constituents in the plant, including potassium, were virtually equal among the plants grown on soils supplied with potassium fertilizer at different levels. In the plants cultured in solutions, chemical compositions of the plant did not differ significantly with the concentration of potassium in the nutrient solutions, except for the potassium content. The plants reared in potassium rich solutions contained a higher amount of potassium in comparison with the plants grown in potassium deficient solutions. These results indicate that level of potassium fertilizer did not affect remarkably the chemical composition of the rice plant and that the growth of larvae is not affected by the potassium content itself of the host plant.
It is suggested that application of potassium fertilizer to a paddy field also may not affect the growth of the rice stem borer larvae, under natural conditions.

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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.

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Effects of temperature on the development and the mortality of the southern green stink bug, Nezara viridula and the oriental green stink bug, N. antennata were studied under a series of constant temperature. Relation between rearing temperature and the colouration of the 4th and 5th instar nymphs in both species was also observed.
1) The relation of rearing temperature and the development in both species can be expressed by straight line, if reciprocals of incubation period and larval period, i.e., the developmental velocities are plotted against temperature.
2) In both N. viridula and N. antennata, the developmental zero and the total effective temperature are obtained as follows:
3) Within a temperature range used in this experiment, the zone of favourable temperature for development from egg to the emergence of imago seems to lie between 20 and 30°C in N. viridula and between 22.5 and 27.5°C in N. antennata. The optimum temperature for development is near 30°C in the former species and near 27.5°C in the latter.
4) In both species, individuals bearing melanic pattern occur more frequently with the fall of temperature (Figs. 3 and 4), indicating that temperature can be regarded as the main factor responsible for the variation of the body colour of the 4th and 5th instar larvae.

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In the orchards around Sapporo, the population of Panonychus ulmi was exceedingly dominant as compared with other four species, Tetranychus viennensis, Tetranychus telarius, Bryobia praetiosa and Bryobia rubrioculus, in the year of 1957. The seasonal prevalence of P. ulmi was showed in Fig. 1. The seasonal change of age distribution of this species on the apple leaf takes place generally as follows:
Larva association→Larva-Nymph association→Adult-Egg association→Egg association→(Nymph association)→Egg association→(Egg-Larva-Nymph association)→Egg-Nymph-Adult association→Adult association.
The apparent sex-ratio of P. ulmi shows that it has higher ratio in the female or balanced ratio in both sexes. It is variable during the season.

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Some natures of the unknown growth promoting factor required by the smaller tea tortrix larvae, Adoxophyes orana FISCHER VON RÖSLERSTAMM, was elucidated by comparing feeding response of newly-hatched larvae to the synthetic food media containing various amount of boiling water extract of tea leaf and the growth response of the larvae on them.
The rate of larval growth was positively correlated with the dietary amount of the extract, the optimum range of the extract was considered to be 15 to 18 per cent of dry diet. But, percentages of larvae established on the food media were not correlated with amount of the extract. It was concluded that an unknown growth promoting factor contained in tea leaf was a nutriment essential for larval growth, but had no activity as a feeding stimulant.

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1. Xanthine enzyme system in lepidopterous insects was demonstrated to be dehydrogenase but not oxidase.
2. The enzyme activity was high in the fat body and Malpighian tube, but was low in the mid-gut wall, whereas it was negligible in the rectum, integument and blood.
3. In the Periplanela americana, the enzyme activity was found in the Malpighian tube, fat body, hind-gut wall and mid-gut wall, but not in for-gut wall.

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