A survey was carried out in Wakayama, on some factors attributed to the behaviour of the overwintered larvae of the mealy bug, Pseudococcus kraunhiae KUWANA at the time of dispersement to the buds of the Japanese persimmon, Diospyros kaki L., from their hibernation in the spring. One tree, plantation of which took a place in 1942, was selected in an orchard and the number of all the bugs, buds and twigs was counted. The frequency distributions of the number of the bugs per bud and the number of the bugs per twig were well represented by Polya-Eggenberger's distribution type. The parasitism of the bugs was significantly heavy on the apical buds. The number of the bugs and buds per twig increases proportionatelly with the length of the twigs, but the number of the bugs per bud did not increase.
When 20 or 40 twigs were sampled from the tree at random, average number of the bugs per bud or per twig did not differ from the results of the survey on all twigs of this tree, but the differences appeared on the type of frequency distribution of the number of the bugs per bud, on the number of the bugs per twig classified by its length, and on the number of the bugs per bud classified by its position on a twig.
The survival rate of the bugs until maturation, from April 18 to June 24, was significantly higher on apical buds than on other buds.

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Citrus flat-headed borer, Agrilus auriventris auriventris, is an important citrus pest in southern Japan. Sometimes this species increases in a restricted area and heavily infests citrus trees.
In this paper, the author wishes to show the development of ovary of these adult beetles rearing in glass vials under laboratory conditions. The beetles that emerged from Hassaku orange tree in August and September were used for dissection of ovaries.
The longevity of adult beetles that fed on citrus leaves was about 10 days average, and 5 days without any food. The eggs were not observed in ovarioles just after the time of the adult emergence. In feeding individuals, the ovum was formed in 5 or 6 days after emergence. But the full grown eggs were observed in 8 or 10 days and the oviposition began in 10 or more days after emergence. On the other hand, in individuals without food, any full grown ovum was not observed.
From these observations, it seemed that the eggs in the ovary of these beetles were formed slowly and many of the individuals could not live out to meet the time of oviposition.

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According to the previous findings that coumarin-3-carboxylic acid and 6-coumarinylamine coumarin-3-carboxylate have a strong hypothermal action and toxic action to rats, a study was made in an effort to apply these compounds as rat poisons. These compounds and in addition, thallium coumarin-3-carboxylate have superior toxic effect on rat (Rattus norvegicus var. albinus) and mouse (Mus musclus), and have a little toxicity for domestic animals such as dogs and cats. Thus, there may be a possibility of application of these coumarins as rat poisons for practical use.

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In order to affirm the existence of an aggregative behaviour of the silk-worm in a certain period, an experiment was carried out. The silk-worms used in summer of 1961 and 1962 were Shi-124×Nichi-124, in autumn of 1961 (2:4)×(5:4), and in spring of 1962 Gimpaku×Zuiko. These strains have been used widely. for breeding in the sericultural industry in Japan.
The observation was made on the silk-worms, which initially were placed separately in a space with aframe; movement of individuals was observed and the number of solitary ones was recorded every five minutes for an hour. The ratio of the number of solitary individuals at the end of the one-hour observation ranges 11 to 31 per cent. This shows aggregative rates of the worm were 69 to 89 per cent. In the first thirty minutes, the number of the solitary individuals rapidly decreased, and contact or approach by two individuals occurred.
Finally some large groups containing four to six individuals were formed which, however, showed no further development. If an individual came in contact with other individuals, swinging movement of the first two body segments became less remarkable and the worm became almost immobile.
The peculiar character in aggregation of the silk-worm described above was observed regardless of seasons or instars. Younger individuals were more active than older ones; former fell into aggregation more rapidly, but the dispersion was even more rapid and oftener than latter.
Thus, an individual, continuing the trial and error movement, gets a chance klinotaxically to contact and approach each other and is led to an aggregation. From the present results an existence of the aggregative behaviour of the silk-worm is recognized.

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Seasonal variation of population of the pine shoot moths and their hymenopterous parasites in Aichi, Central Japan, was determined by examining the infested shoots collected from plantation of the Japanese black pine, Pinus Thunbergii PARL. Throughout a year, Evetria cristata WALSHINGHAM was the dominant species among four species of pine shoot moths found, and responsible for a large part of infestation in the pine shoots. Rhyacionia duplana simulata HEINRICH was the sub-abundant species, particularly in June and July, but level of population densities of Dioryctria splendidella and Eurhodope sp. were the lowest throughout a year. Among the hymenopterous parasites, Lissonota evetriae UCHIDA, Temelucha sp. and Pediobius sp. were fairly dominant.

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Age-specific fecundity, survival rate and proportion of the sterile females in the population of Nezara viridula that belongs to the first and the second generations were studied in field cages. Larvae of the fifth instar were kept in each cage and examined at 3 day intervals. Every newly emerged adult was marked to obtain an individual record of life span and mating behaviour. Eggs deposited in the cage were thoroughly examined at each survey and eradicated after taking count. Relation between mating frequency and egg laying obtained from the daily examination of 15 pairs of the first and 27 pairs of the second generation in the laboratory was used for the estimate of the fraction of sterile females in the field cages. Longevity of adults in the field cages was 18.7±14.2 days among males and 27.5±19.2 among females, on the other hand 36.6±10.9 and 45.4±12.2, respectively in the laboratory. The survivorship curves of the cage populations are characterized by rather a concave type or a steep fall at the early period of adult life. After passing this period, adults die almost at a constant rate until about 60% death of the total population results and the rate suddenly increases along with the aging of adults.
There is a great variation in sexual activity among individuals of both sexes. And about half or more adults of both sexes could not be observed during mating. As mating behaviour of females is closely related to egg laying, the fraction of sterile females among those non-mating individuals was estimated from the percentage sterility obtained in the laboratory populations in regard to the mating frequency. It was calculated that a total of 43% of the females had died without reproduction, 33% of which was ascribed to the death in the preoviposition period and 10% was considered to be sterile showing no apparent difference from normal ones. In addition to this, it is suggested that there are males that are sexually weak or impotent in much the same proportion as females.
It is postulated that the low fecundity accompanied by high density should not be interpreted simply as a shift of mean fecundity per female, but such a shift of mean is attributable to a decrease in mean fecundity per reproducing feamale on one hand, and to an increase in proportion of sterile females in the pertinent population on the other. Using the values of mortality obtained from life tables, net reproduction rate (Ro) was calculated and gave the values of 0.4 and 2.4 for the first and the second generations, respectively. Therefore, the decrease in the population of the first generation is compensated by the increasing trend in the second generation which develops principally in the paddy fields of early planting rice. When the mortality of immature stages is 97.57%, the value of Ro becomes unity. Values of intrinsic rate of natural increase (r) of the southern green stink bug were shown in Table 6 with varying degree of mortality and duration of immature stages.

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In the armyworm, Leucania separata, the black larvae appeared in crowded population are different in many respects from the pale larvae in sparse population. This paper deals with the different reactions of these two types of the larvae to some mechanical stimuli.
When the larvae were dropped onto an illuminated field, they remained immobile for some time and then began to escape away. Most of the black larvae resumed their activity within one minute since being dropped, while a considerable percentage of the pale larvae showed a prolonged immobilization over five minutes. The difference was similarly observed in both experiments in which the larvae were dropped individually in a group.
After the recovery from the inactive state, the pale larvae tended to move into dark place more than the black ones. The photonegative tendency of the former was, however, reduced considerably when a group of the larvae was dropped simultaneously.
The difference was also observed in their grasping behaviour; the pale larvae clinged more firmly to the plant than the black ones when exposed to a strong wind.
These results are to be regarded as additional evidences of the fact that the pale larvae are passive and station-keeping, while the black ones are active and mobile in habits.

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Population growth, survival rate and fecundity of apterous Rhopalosiphum maidis were examined on wheat and barley seedlings growing under different nutritional conditions. Barley plants grown under all the cultural conditions tested always gave more rapid population growth, higher survival rate and greater fecundity of the aphid than wheat plants. On wheats, the aphid increased its population more rapidly on seedlings cultured in low-nitrogen solution (termed as low-N wheat) than on seedlings grown in high nitrogen solution (high-N wheat) and in manured soil (soilplanted wheat). Survival rate and fecundity of the aphid were highest on the low-N wheat, lower on the high-N wheat and lowest on the soil-planted wheat. The suitability of barley and wheat seedlings grown under different nutritional conditions as a host plant are arranged as follows: soil-planted barley=high-N barley>low-N barley>low-N wheat>high-N wheat>soil-planted wheat.
The suitability of wheat seedlings as a host plant seems to correlate positively with sugar content and negatively with nitrogen content of the seedlings. The wheat seedlings may contain an antibiotic substance against Rhopalosiphum maidis, synthesis and/or acitivity of which reduced under such conditions as nitrogen deficiency.

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The residual behavior of Bayer product S 4741 was examined by use of ³²P-radiotracer. It was found that the insecticide was rapidly penetrated and translocated into citrus and rice plant, irrespective of any application methods. The degradation rate of the insecticide, examined by chloroform-water partition coefficient of radioactive material in citrus leaves, had a similar tendency in both cases of spray and topical applications. In orange fruit, the insecticide residue was higher in peel than juice on the eighth day after the application. The accumulation of the insecticide in top leaves of apple tree after the topical application on the stem base was similar to that in citrus leaves, but the degradation rate of the insecticide was slow as compared with that of citrus leaves.
The behavior of the insecticide sprayed on garden radish and sugar beet, was rather different between both plants, and the accumulation of radioactive material in root was higher in sugar beet than garden radish. This fact would be due to the difference of growth rate during the experimental period. The partition coefficient of radioactive material in roots was always lower than that in leaves of both plants. When the roots of rice seedlings were dipped into the water emulsion of the insecticide before the transplantation, the insecticide was rapidly taken up by the seedlings. About forty-one per cent of available insecticide in the water emulsion was taken up by the seedlings during 24 hours' root application. When the insecticide suspension was poured into the paddy water after the transplantation of seedlings, the major part of insecticide was distributed in leaf sheath and leaf blade but the distribution in root was very low. This fact may show that the insecticide penetrated into plant body mainly through the surface of leaf sheath but not through root.
After the penetration of the insecticide into plant tissues, mercaptosulfur moiety of the insecticide molecule was oxidized to produce the sulfone such as the case of systox. Phosphoric acid and dimethyl phosphoric acid were found as the hydrolysis products of the insecticide by ion exchange chromatography, and the production ratio of these metabolites was different among the test plants.

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[in Japanese]

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