The white back planthopper, Sogata furcifera, and the brown planthopper, Nilaparvata lugens, have been well known as very serious pests of the rice plant in Japan. For a long time, however, it has not been known where these species spent the winter.
Recently, MIYAKE and FUZIWARA (1962) found experimentally that there were diapause in eggs of these species. It is interesting in relation to the problem of hibernation in both species. Since their paper seems to be insufficient in regard to the factor analysis of the induction of diapause in eggs of both species, the present author intended the experiments to make clear these uncertained points.
1. White back planthopper
The adult just after the emergence was reared separately (one pair) or together (ten pairs) in a glass tube with supply of headed grass of Panicum crusgalli var. submutica under the photoperiod of 8 hours illumination and low temperature of 15°C. Then greater part of their deposited eggs entered into diapause, even if they spent their larval life under the condition of high temperature of 27.5°C, long day of 16 hours, and crowding, which is very favourable condition for their development.
It is considered that the adult receives the stimuli of induction to diapause gradually, when they spent their adult life under the condition mentioned above. Because, preoviposition period of these adults was rather prolonged and the percentage of diapausing eggs was gradually increased with lapse of adult life.
Most of the diapaused eggs stopped at the stage of eye pigmentation of their embryonic development.
2. Brown planthopper
A similar result was also obtained in the brown planthopper. When the adults were reared separately in a rearing tube (one pair) feeding under short day of photoperiod and low temperature of 15°C, some of their deposited eggs were not hatched and their development was retarded, even though they spent their larval life under the condition of high temperature of 27.5°C, long day of 16 hours, high population density and leaf sheath of rice plant after heading as larval food. All of the retarded eggs were at the stage of yellow spot.

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The age distribution, mortality and the development of ovaries of overwintering arrowhead scale, Prontaspis yanonensis collected from 26 stations of Nagasaki Prefecture were examined three times viz, in late January, mid March and early May of 1963.
Most of the samples examined in January and March show that the overwintering population of this scale consists of 2nd instar larvae and full grown male larvae and juvenile and mature female adults. But some of the samples collected from the stations at Shimabara Peninsula and Nishisonogi Peninsula contained 1st instar male larvae and 2nd instar female larvae.
Winter mortality of this scale was showed by the proportion of living individuals against the total number of living and dead individuals. The mortality of the 1st and the 2nd instar larvae was 70-100%, of juvenile adults was 20-60% and of matured adults was 10-30% among female scales. Significant fluctuations of mortality between stations were not observed.
Almost all the samples collected in early May were consisted of mature female adult with exception of the ones came from the the station of southern part of Shimabara Peninsula, Iki Island, and Tsushima Islands. In these stations, juvenile female adults were found. It seems that these juvenile individuals overwintered at the stage of 2nd instar larvae.
In early May, the 1st brood of this scale bigan to hatch out. Number of the establishing 1st instar larvae per adult females were larger at some stations such as Kuchinotsu, Shimabara (Shimabara Peninsula), Ôseto (Nishisonogi Peninsula) and Mogi (Nomo Peninsula).
Development of ovum were examined in March by dissection of adult ovaries. Number of developing ovum in ovarieles per one female was about 5 at two stations in southern part of Shimabara Peninsula and about 2 at the other stations.
From these observation, the local variation of age distribution and development of ovum in overwintering arrowhead scale were recognized. In Nagasaki Prefecture, district of south western seaside such as Shimabara, Nomo and Western Nishisonogi where show the overwintering of young larvae and development of ovum in adult females, differ from the other districts. These districts bordered by the isothermal line of mean temperature 16.5°C.

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In many experiments of drugs and poisons on animals differing in size but otherwise similar, the same dose is given to each individual, as if its action were independent of body size, e.g., toxicity test with house flies, or doses are proportioned directly to the body weight, e.g., acute oral toxicity test with mouse. Instead of an arbitrary correction such as the latter, a size factor for equalizing individual differences in body weight can be determined experimentally for each drug by multiple regression. When the response y is a measurement, size factor w^h can be estimated from the regression of y upon the dose per animal (x₁=logd) and its body weight (x₂=logw) by transforming the basic regression equation from Y=a'+b₁x₁+b₂x₂ or Y=a'+b₁(log d+b₂/b₁logw) to Y=a'+b₁log(dw^h) where h=b₂/b₁; b₂ is almost always negative.
This approach was illustrated by BLISS (1936, 1961) in details using the experimental data on the rate of toxic action of sodium arsenate in larvae of silkworm moth by CAMPBELL (1926). The writers applied his method of statistical analysis to the experimental data obtained from the rate of toxic action of pentachlorophenol in the “Dojo” fish. Each fish was dipped in aqueous solution of prescribed concentration and the lethal time was measured in minutes. The variates for analysis are the log dose per fish x₁=(log p.p.m.), its body weight x₂=log grams, and the rate of toxic action y=log (100/minutes survival).
One of the 100 fishes at a concentration of 25p.p.m. has been omitted after statistical test as outlier, subject to physiological processes present in the other 99 fishes. As computed in the paper, the multiple regression equation is Y=-0.05834+0.58337x₁-0.16823x₂. From the ratio of the two partial regression coefficients, h=b₂/b₁=-0.28837, it is concluded that k times larger fishes required relatively k^0.288 times less PCP than that indicated by the ratio of their body weights to kill them in the same time as the smaller fishes. Here, h=-1 means that the doses should be proportioned directly to the body weight and h=0 means doses are independent of body weight. For a graphic test of linearity, the log dose for each individual was computed as z=x₁-0.28837x₂ in Table 1, and y plotted on the ordinate against z on the abscissa in Fig. 1. It has been fitted with the line Y=0.4936+0.5859(z-0.9452), the slope differing from the original b1 by rounding errors. The fidulcial limits of h and z were calculated and the test method on a suspected outlier was also explained.

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Lissonota evetriae UCHIDA was a solitary internal larval parasite and its life history in the Tokyo University Forest in Seto was;
where, L: Larva, P: Pupa, A: Adult.
The parasite remained as the 1st instar larva from May to August. The fully grown larva spun a cocoon immediately after it killed the host larva in October.
The population densities of both host and parasite per tree were counted in 1961 and 1962, and it was made clear that the greatest decrease of the parasite population within a generation took place in May to June when the parasite larva was in early stage of the 1st instar. The decrease was most probably due to the death of many host larvae, which inevitably caused the parasite larvae to die.

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In course of the studies on feeding and nutrition of phytophagous insects, the present investigation was undertaken to determine if the different food values of several host plants for a polyphagous insect could be analyzed by means of measurements of food utilization. Two groups of the last instar larvae of the cabbage armyworm, Mamestra brassicae L., were reared on leaves of beet and sweet-potato plants, respectively, and the data were recorded on dry matter and nitrogen balances.
1. The mean nitrogen contents of the beet leaves and sweet-potato leaves were 3.83 per cent and 2.80 per cent, respectively.
2. The larvae grew much faster on the beet leaves than on sweet-potato leaves. The fresh and dry weight of pupae grown on the beet leaves and their nitrogen contents are also significantly higher than pupae grown on sweetpotato leaves. These indicate that the beet leaves are the suitable food for the last instar larvae of this insect species as compared with the sweet-potato leaves.
3. Although the larvae that were fed on sweetpotato leaves consumed more food during the last instar than did those fed on the beet leaves, the mean value of the daily consumption of food (dry matter consumption per day) was much more on the beet leaves than on the sweet-potato leaves, indicating that the larvae preferred the beet leaves to the sweet-potato leaves. Similar patterns of consumption occurred in regard to nitrogen; the total consumption of nitrogen was much more on the sweet-potato leaves, but the dialy consumption of nitrogen was higher on the beet leaves.
4. During the last instar, larvae that were fed on the sweet-potato leaves excreted larger quantities of dry matter and nitrogen than did those fed on beet leaves. The daily excretion of dry matter was also larger when larvae were fed on the sweet-potato leaves. Taking into consideration that the daily consumption of the sweetpotato leaves by larvae was smaller, it is clear that the sweet-potato leaves were utilized by larvae at a low efficiency as compared with the beet leaves.
5. Utilization percentage of the dry matter by the larvae was 49 per cent on the beet leaves and 24 per cent on the sweet-potato leaves. This indicates that the beet leaves were utilized by the larvae at a higher efficiency twice as much as the sweet-potato leaves.
6. Utilization percentage of nitrogen by the larvae was 32 per cent on the beet leaves and 13 per cent on the sweet-potato leaves. This indicates that the nitrogen compounds in the beet leaves were utilized by the larvae, at a higher efficiency 2.5 times as much as the nitrogen compounds in the sweet-potato leaves.
7. According to the results of the present study, it is concluded that beet leaves were a superior food for the last instar larvae of Mamestra brassicae as compared with sweet-potato leaves, and that although difference of the food values between the two plant leaves was partly due to the higher nitrogen content of beet leaves and the higher preference of the insect larvae for beet leaves, the main cause was the difference between utilization percentage of respective leaves by the larvae; particularly the utilization percentage of nitrogen compounds in the leaves was significant. It seems that the nitrogen compounds in beet leaves has superior quality as a nutrient for the last instar larvae.

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In early 1963 the writers proposed that the structures of the compound eye can be used for the estimation of activities of Lepidopteran adults. In that book, an idea of the use of structures of the eye to estimate moths' activities was presented. However, the detailed meaning and the technique of the eye section were not adequately described. Therefore, in this article a principle of activity estimation and its practical use were explained with the whole groups of moths adding fifty more species. Consequently, two types of activities which exhibit values of 6-8 and 2-4 are newly added to ever known twenty-one types of activities.

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In the previous paper, the author showed the presence of an aggregative behaviour in the silk-worm. This paper dealt with the experiments on the sense organs involved in this behaviour.
At first, for examination of the role of the visual sense, experiments were carried out in a dark-room utilizing the same method as in the previous series. When the results were compared with those of the experiments under the light condition, no shift in aggregative rate (after 60min.) was noticed, being about 85 per cent in darkness and 89 per cent under light. Graphs of these rates also showed similar patterns in both experiments.
Secondly, the role of the contact sense in this behaviour was tested by using several models such as piece of wood, paper or rubber of the same size to the silk-worm. The response of worms to these models was observed. The behaviour of silk-worm individuals against these models was completely different from, and the rate of response was much lower than in the case of mutual reaction among the live silk-worm.
Finally, the significance of olfactory sense was analyzed. Starch paste was applied at the site of olfactory pore openings, and the behaviour of so treated worms was observed. They showed an aggregative rate (after 60min.) of only about 32 per cent. The behavioral conduct was different from that of intact ones which showed an aggregative rate of 83 per cent after 60min. It was therefore apparent that the covering of the olfactory pores influenced anyhow on the aggregative behaviour. Yet, those individuals with their olfactory pores covered did not show any remarkable tendency to loose contact if they had been kept in contact each other from the beginning. They were less dispersed from initial site even after 60min.
From these experiments, it is likely that the visual sense has almost no concern with the mechanism of this aggregative behaviour, and the silk-worms recognize each other by means of olfactory sense and come in contact, then firmly keep contact to induce an aggregative state. It is possibly the contact sense that plays a major role in the lattter process.
It follows therefore that both olfactory and contact senses are involved in the mechanism of this aggregative behaviour of the silk-worm.

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A total of 1, 161 females of the southern green stink bug, Nezara viridula were dissected throughout its active season from April to December in 1962 at an interval of four or five days. Each individual was examined in regard to the following points; (1) degree of maturation of the ovaries discriminating five stages, (2) virgin or mated, (3) non-oviposited or oviposited, (4) appearance of black spots in the ovarioles as an indication of termination of oogenesis, (5) number of eggs contained in the ovaries of mature female and (6) amount of fat body. To check the results obtained from the dissection, censuses were conducted during the oviposition period of each generation to determine the egg laying process relative to time. Capture records of adults by a light trap were employed in interpretation of the seasonal history of the bug.
It was suggested that by regular dissections of females, it was possible to predict the process of oviposition knowing the intervals among percentage curves in regard to the mating, oviposition and black spotted, respectively. The number of generations in a year can be assessed by the dissection even when generations overlap, and the occurrence of an additional generation can be forecasted by dissecting its parents. The relation between the percentage curve of oviposited females and the accumulated percentage curve of the number of egg masses which were laid in the field was available for estimating the fecundity of the natural population. The number of eggs in the ovaries of the mature females corresponded well with the size of the egg masses observed actually in the field. The amount of the fat body considerably increased before and during hibernation. This seemed to be responsible for the hypertrophy of the cells. The differential maturity between the sexes in the hibernating population was suggested.
It was concluded that the changes in the reproductive system provide a useful means predicting the changes of seasonal history in the population of the southern green stink bug and application of this method is promising to other insect pests.

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In the spring generation, considerable difference of the larval development was found between two regional stocks. The progenies from the three-generation area developed rapidly and those from the two-generation area slowly. In the cross between two regional stocks, the larval development in the hybrid generations varied widely, but it resembled to that of the maternal parent. The three-generation stock persisted its inherent characters over the experimental period of 3 years after being transferred into the two-generation area. From these results the existence of the two distinct geographical ecotypes in the rice stem maggot was discussed.

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The experiment was undertaken to determine whether or not reproduction of the apple leaf-curling aphids was affected by the use of gibberellic acid. For this purpose of the study four treatments of gibbereliin were applied on apple seedlings under fluctuating temperature and fluctuating light conditions in a net house. From the over-all arguments, it is concluded that higher level of gibberellic acid was requierd in order to effect a significant reduction in aphid populations. Beyond any doubt, such differences will appear on the differences of the nutritional basis rather than on direct plant growth. In this respect, analyses of reducing and total sugars of apple foliages proved that the reducing sugar was lowered down in the treated plants despite no apparent effect was detected in total sugar. This close linkage between the aphid development and plant nutrition is probably due to the gibberellin application.

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