Population counts of the overwintering females of the arrow-head scale, Prontaspis yanonensis KUWANA, were conducted at nineteen Satsuma (=mandarin) orange orchards distributed over two areas of Shizuoka Prefecture. Fifty-leaf samples were randomly examined on each of five trees which were randomly chosen from each orchard. Examination of the data showed following results.
1) A quadratic curvilinear relationship between the mean and the variance (Fig. 1) suggested the contagious distribution of the mature adult of the arrow-head scale. According to the BLISS & OWEN'S (1958) method, a common k of the negative binomial distribution for all the 50-leaf samples (excepting those shown by circles with oblique lines) was estimated to be 0.4611 (Table 1). Distributions of the second instar larvae were also well represented by the negative binomial series with a same common k (Fig. 3, solid circle), while in distributions for total insects involving all the developmental stages, variances were more scattered (Fig. 3, hollow circle).
2) The analysis of variance for fourty-five trees from Nishiura area made after the log-transformation of the data showed that both the inter-orchard and the inter-tree variances were highly significant (Table 2). Because of this large inter-tree variance, it was suggested that 20-leaf samples from each of 20 trees would be needed for 10 per cent precision (Table 3).
3) In the negative binomial series with a common k, mean number of insect per leaf can be estimated from the per cent of insect-free leaves to the total leaves examined. Relationship between the mean and the per cent of insect-free leaves was shown in Fig. 4.
4) A preliminary test of the sequential plan was made using leaf-samples randomly taken from coded populations of which means were known. The results showed clear usefulness of the sequential technique in the field surveys of this insect (Fig. 5). The average sample number curves were calculated following MORRIS' (1954) formulae (Fig. 6).

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In the previous paper (1962 a), the authors studied the influence of larval aggregation of the rice stem borer, Chilo suppressalis, upon its survival. In the present paper, the authors intended to know the influence of the synchrony of hatching of individual eggs within an egg mass on the formation of larval group in a paddy stalk and on the behaviour of larvae from hatching to aggregation at the first feeding site. These experiments were carried out under the natural condition of room temperature and natural daylength.
The results obtained are summarized as follows.
1) Hatching of eggs within an egg mass of large size was well synchronized and it took 13 minutes in average for completion of hatching in contrast with a small one of 20 minutes, in which the variation of hatching time between first and last in each mass was great.
2) When an egg mass of large size was separated into some pieces at 2 days before hatching, any neighbouring piece did not hatch one after another, but hatched independently and it took time more than 2 hours from the beginning of hatching of the first piece to the completion of the last one.
Therefore, the time from hatching to its completion was greatly protracted.
3) when several eggs within a large sized egg mass was killed by needle at random 2 days before hatching, the time between the first and the last hatching in a mass was also greatly protracted and it took time more than 1 hour.
4) At the 3rd day after hatch the degree of larval aggregation in a rice plant stalk was maximum in the large sized egg mass and the minimum in the mass where several eggs were killed randomly by needle.
5) In most instances, the larvae tended to move toward the tip of rice plant leaf. Some remained motionless there, others turned around and followed the leaf surface back to the base of the leaf and one of these larvae which reached to the feeding site (leaf sheath), wandered around here and there for a moment, thereafter it confluented with others. The larval group was gradually enlarged in its size and established at the feeding site. An isolated larva could not feed.
When the hatching of eggs within an egg mass was well synchronized, the degree of larval aggregation was high. On the other hand, if the synchrony of hatching was disturbed by such a factor as parasitization, establishment of aggregation was also disturbed. It is concluded that synchrony of hatching and the behaviour of newly hatched larvae influence the size of larval group and larval survival.

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A. funeralis lays eggs in mass on the leaf of bamboo-grass. After larvae keep in a compact aggregation up to the third instar, they gradually disperse out.
The present laboratory experiment was carried out to clear up the influences of individual number on the survival and development of the larvae.
The larvae hatched from an egg-mass were reared at 1, 5, 10 and 20 individuals per vessel under the constant temperature of 27.5°C and the natural day length in laboratory.
When the larvae were kept isolated, some of them did not feed and then died. In the first instar, they showed the highest mortality (15%) of the densities tested.
On the other hand, when 10 or 20 individuals were reared together, they did not die at all during early instars, but their mortality became higher than less crowded individuals after the third moult.
The larval duration intended to increase with increasing the number of individuals in aggregation, because the larvae reared at 5, 10 and 20 individuals had longer duration and more instars. Especially, they had as long duration as isolated one up to the third instar but took longer at the forth instar.

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1. In this paper the writer gave an account of observations on the habits of oviposition of Pieris rapae crucivora, Plusia nigrisigna and Mamestra brassicae on cabbage plants.
2. These species deposit their eggs on all leaves of young plants but only on the leaves of middle and upper parts in aged plants. However, even in aged plants, Pieris rapae crucivora and Plusia nigrisigna deposit some eggs on the lower leaves when the density of adults in the field is high.
3. Almost all of the eggs of Pieris rapae crucivora were deposited on the under surface of leaves. But a few were deposited on the upper surface of the middle and upper leaves in the third and fourth brood. The latter fact is probably due to the increasing number of eggs deposited on a plant; i.e., about one quarter of the eggs per plant were on the upper surface at the time of peak oviposition in the fourth brood. Similar results were obtained in Plusia nigrisigna, though the number of eggs deposited on the upper surface showed no such close correlation with that on the under surface as in Pieris rapae crucivora.
4. Mamestra brassicae usually deposit their egg-masses on the under surface of the leaves, and an egg-mass deposited on lower leaf contains more eggs than those on upper leaf.
5. Pieris rapae crucivora and Plusia nigrisigna showed a tendency to deposit their eggs on the leaves in every direction in a plant. On Mamestra brassicae, the obtained results did not ascertain this point.

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It has been known that the appearance of the first generation larva of the arrow-head scale, Unaspis yanonensis KUANA shows two prominent peaks of appearance under the natural condition. It may be an important problem to clarify the mechanism of such unusual occurrence of the larva, from the view point of the control of this insect.
In order to make clear reason why the fluctuation curve of the larval appearance in the first generation is divided into two parts, the following investigations were carried out from 1961 to 1962.
The results are summarised as follows:
1. The leaves on which arrow-head scales live, were collected periodically, and the stage in which the insect hibernates was ascertained. From the results, it was found that the scale insect hibernates only in the adult stage of the female. According to the investigation on the degree of maturity during the hibernating period, about 80 per cent of the adults were matured and the others were inmature. Although the time of appearance of the larvae derived from these inmature adults was almost equal to that from matured, the number of larvae occurred from the former was extremely small compared with the latter.
2. From the observation it was ascertained that the appearance of larvae was initiated, with a few exceptions in middle of May; and the peak of first larval appearance came at the end of May. At the beginning of June the scale insect ceased to produce larvae for about 9 days and after this resting period it commenced to produce larvae again making second peak of appearance.
3. In order to make clear the cause that the larval appearance stops once in the first generation period, the ovary of the adult insect reared on the orange fruit at 25°C was examined at regular intervals.
From the results, it was ascertained that the arrow-head scale has the ovovipiparous characteristic and the egg stays in the ovary until the embryonic development is almost completed. Further, it may be interesting that the ovary ceases to produce eggs when they reach maximum number and it becomes active in egg production again when the egg-laying is initiated.
4. It seems probable that the occurrence of two peaks of larval appearance in the first generation is due to the resting period observed in the process of egg production in the ovary.

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1) The preference of sap eating drosophilid flies to fruit in nature was investigated, locating fruit traps near and remote to a bleeding Quercus tree. The fruit eaters are thought to be selectively advantageous in having higher potentiality of utilizing diverse kinds of food environments, as compared to the sap eaters. Evident replacement due certainly to competition during about ten years was shown between some closely related species having equal sap preference.
2) Within a year the ecological niche occupied by each species tended to become broader in the warmer season, due probably to the saturation of the primary habitats by the existing populations and to the invasion of excessive populations into the poorly occupied microgeo-graphical or microecological niches of the secondary habitats, thus resulting a balanced cohabitation.
3) The sex ratio (_??_/_??_×100) of the flies collected either at sap or at fruit was higher than that of the flies collected at both sap and fruit. Seasonal fluctuation of sex ratio was roughly proportional to the population size under coexistence of sap and fruit sources. It became, however, increasingly high in the later seasons, despite the population size was decreasing, under separated food sources. The establishment of breeding sites for the occupants seems to have been remarkable in this case.
4) The sap exudation is thought to have been an original diet for drosophilids, because the essential sap eaters are apt to be primitive in morphological features, relatively narrow and scattered in distribution and bradytelic in presumed phyletic changes.
5) Some morphological and behavioral features of adults and larvae adapted to the sap eating nature have been explained.
6) A suggestion was given from standpoint of applied entomology on a controlling effect of the coexistence of wild and cultivated food sources upon the herbivorous insect pests injurious upon these plants.

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³²P-labeled Baycid was sprayed on the three kinds of rice plant which were different in growth stage, and the behavior of the insecticide on and in rice plant was examined.
1. The hydrolysis rate of Baycid in rice plant seemed to be slower than that of methyl parathion or malathion. Baycid disappeared rapidly after the application in the three kinds of rice plant, and only about 10 per cent of chloroform extractable metabolites remained as Baycid 6 hours after the application.
2. Chloroform extractable metabolites of Baycid in rice plant which were detected throughout the experimental period, consisted mainly of PS-sulfoxide and PS-sulfone, and the appearance of the oxidation products as PO-form seemed to be a small even if existed.
3. When Baycid was sprayed on the rice plant at a few days before heading stage, the Baycid metabolites tended to be accumulated to ears and grains. The content of the metabolites detected in the rice grains 29 days after the application was about 7 p.p.m., as expressed as Baycid. The metabolites in the rice grains were concentrated in bran but not in polished rice and husk.
4. The water extractable metabolites in the rice grains 14 days after the application were separated by ion exchange chromatography, and the existence of phosphoric acid, thiophosphoric acid, O, O-dimethyl phosphoric acid, O, O-dimethyl thiophosphoric acid, O-methyl O-(3-methyl-4-methylmercaptophenyl) thiophosphoric acid and one unknown metabolite were found. It was remarkable that the proportion of monodemethylated compound of Baycid is relatively high.

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The behavior of ³²P-labeled Baycid was compared between tea leaves and cabbage leaves, and the residue of Baycid or its metabolites in tea leaves before and after the manufacturing process of green tea was also examined.
1. It was probable that the penetration rate of Baycid into leaf tissues was more rapid in cabbage leaves than in tea leaves, and that the metabolic rate of Baycid was also rapid in cabbage leaves.
2. In tea leaves, PS-sulfoxide and PS-sulfone was detected as the main metabolites of Baycid and the appearance of the other chloroform extractable metabolites was a little, while in cabbage leaves, the distribution of the metabolites was rather different from that of tea leaves, and the appearance of the metabolite which suggested the oxidation of thiophosphate to phosphate was clear.
3. The absolute amount and the distribution of the metabolites in green tea were hardly changed before and after the manufacturing process of green tea.

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Most of the adults of the third generation of Nezara viridula pass the winter in the dense crowns of quickset hedge of Cryptomeria japonica, juniperus chinensis and in the crevice of leaves of Yucca recurvifolia. Mean mortality relative to different wintering quarters were 64.57 and 37.99%, 86.06, in cryptomeria, yucca and Chinese juniper, respectively. Survival rate of female adults was 11% higher than those of male. This differential mortality relative to sex alters the female ratio of the population is seen before and after hibernation from 48.3 to 54.4%.
Validity of changes in sex ratio caused by the differential mortality of the sexes was also confirmed by the censuses conducted in a paddy field for the population before hibernation and in rape and wheat fields for the population after hibernation. Difference in mortality relative to the sorts of shelter becomes significant for the periphery population being largely depend its persistence upon the possibility of finding well protected wintering quarters. It is also important from the viewpoint of the dynamics of Nezara population that the loss caused by the winter mortality is somewhat balanced up by the differential mortality of the sexes which cames in favour of females. It was shown that the expected maximum rate of increase from the reproductive adults of the second generation to the hibernated adults of the third generation will be 2.15.

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