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[in Japanese]

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[in Japanese]

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As a part of the eradication program for the Japanese encephalitis, which has been carried out by the Miyagi Prefectural Government, writers have been studying ecological problems of the mosquito, Culex tritaeniorhynchus, a vector of the disease. Kato's animal baited traps were set at 14 cow sheds at various sites (listed in Table 2) of Miyagi Prefecture, Japan in the summer of 1965 (dates of collection listed in Table 1), so that the invading mosquitoes were able to be collected. Following 8 species of mosquitoes were collected throughout the investigation period; Anopheles hyrcanus sinensis, Culex tritaeniorhynchus, Culex pipiens pallens, Aedes vexans nipponii, Armigeres subalbatus, Aedes flavopictus, Culex hayashii and Culex orientalis (Attached Tables 1 and 2), of which former 5 species were abundant (abundant species). The seasonal abundance of mosquitoes obtained in 1965 (Figs. 1 to 11) was discussed and compared with the results obtained in 1963 and 1964 with the abundant species. The results were summarized as follows : 1. From the species-number relationship of the mosquito population which invaded in the cow sheds (Figs. 12 to 14, Attached Figs. 1 to 4), the general mode of succession of the mosquito population in Miyagi Prefecture proceeds; Aedes vexans nipponii dominant→Anopheles hyrcanus sinensis dominant→Culex tritaeniorhynchus dominant, from early to middle summer and does inversely from middle summer to fall. 2. The mode of succession of the mosquito population structures can be grouped into four (Fig. 15) : i) the area where the population ends with the Culex tritaeniorhynchus・Anopheles hyrcanus sinensis (CT・AN) phase ; the mixed culture type (rice and other crops) area in southern part of the prefecture, for example, Kakuda and Iwanuma. ii) the rice paddy field area in northern parts of the prefecture where the population ends with the Anopheles hyrcanus sinensis・Culex tritaeniorhynchus (AN・CT) phase, for example, Furukawa, Tome, and Wakayanagi. iii) the area around the ii)-area where the population proceeds at most to the Anopheles hyrcanus sinesis (AN) phase, for example, Iwadeyama, Wakuya, and Tsukidate. iv) the urban area of the middle cities along the coast of the Pacific Ocean where Culex pipiens pallens participates as a dominant species, for example, Shiogama, Ishinomaki, and Kesennuma. 3. Culex tritaeniorhynchus emerges earlier in season and keeps high population levels throughout season in 1964 when the high incidence of the Japanese encephalitis was observed (Figs. 16 and 17). 4. The percentage rate of the number of Culex tritaeniorhynchus to the total number of Culex tritaeniorhynchus and Anopheles hyrcanus sinensis in 11 localities in 1963, 1964, and 1965 is illustrated in Fig. 18. In this figure, the relative abundance of C. tritaeniorhynchus to An. hyrcanus sinensis is high in 1964. This high rate in the early season could be used for the prediction of the abundance of C. tritaeniorhynchus which is a main vector of the Japanese encephalitis.

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As the genus Horia Kano, Field et Shinonaga, 1967 (Diptera, Sarcophagidae) revealed to be a homonym of the Horia Fabricius, 1787 (Coleoptera, Meloidae), Kano and Shinonaga propose a new generic name Horisarcophaga. The type-species is Sarcophaga oitana Hori, 1955.

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During the period from January to December in 1965 and 1966, investigations on the annual succession of mosquito larvae occuring in tree holes were made in a zelkova forest in the suburbs of Ashikaga City, Tochigi Prefecture. 1) The mosquito larvae and pupae obtained were 1, 029 individuals in 1965 and 945 individuals in 1966, and they were classified into 3 genera and 3 species in every year; Uranotaenia bimaculata 81.6% (1965) and 89.7% (1966), Aedes albopictus 9.3% and 5.4%, and Tripteroides bambusa 9.0% and 4.9%. 2) The seasonal prevalence of the mosquito larvae and pupae collected in both years was summarized as follows. Ae. albopictus and Tr. bambusa appeared first in mid-April; the former was collected until mid-October, while the latter until late September. Ur. bimaculata occured first in early July, and increased suddenly in number in early August when the above two species declined in number. Thereafter, this mosquito reached the maximum abundance during the period from late September to mid-November, and disappeared after the middle of December. 3) None of the mosquito larvae overwintered in the tree holes investigated, because the water of them dried up or froze in a frigid winter.

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During a period from June to December, 1964, an investigation was carried out on mosquitoes inhabiting in the septic tanks in Kanagawa Prefecture and the results were summarized as follow. 1) In the cases of 1, 315 septic tanks which were widely distributed in Kanagawa Prefecture the mosquitoes were found in 467 of the cases (35.3%). Local difference of the occurrence was little significant. 2) Frequency of the mosquito occurrence in two types of the septic tanks was higher in the modified types than that in the standard type. 3) The mosquitoes were identified as Culex pipiens group, Armigeres subalbatus and Culex kyotoensis. Among them, Culex pipiens group was the dominant inhabitant in the septic tanks and sometimes it was found with Armigeres subalbatus in same tanks. Culex kyotoensis was collected only from two tanks which are situated aside of Lake Ashinoko, Hakone National Park. 4) Concerning problems of Culex pipiens group found inthe septic tanks, the autogeny of adult females and the DV/D ratio of male genitalia were examined. For this purpose, pupae and 4th instar larvae were collected as materials from 33 septic tanks in various localities and cultured during about 10 days in the laboratory condition. 5) According to the features of both autogeny and DV/D ratio, Culex pipiens group found in the septic tanks was able to subdivide into two forms, pallens and molestus. In most cases, the mosquitoes were found in a mixing population of two forms in most of the habitats with its ratio being not constant. In some cases, however, the habitats were occupied by only one of the mosquito, pallens or molestus. 6) It is quite probable that the septic tanks are demonstrating not only a considerable significance as a breeding site of the mosquitoes, but these are also playing an important role on the natural selection from pallens to the molestus-form.

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1. In order to determine the vectors of bovine Thelazia in this country, studies were made at several localities and two species of flies were determined. In an examination in Hokkaido throughout a year, only females of Musca convexifrons harboured thelazian larvae at the rate 2.04%, 65 flies out of 3, 183; and on Miyake Island of Tokyo in September, females of the same species harboured thelazian larvae at 0.53%, 7 out of 1, 310. At Oume of Tokyo, from May to November, Thelazian larvae were found from only females of Musca hervei at the rate 0.4%, 8 out of 2, 003. 2. Comparing the ability of transmission of bovine Thelazia between Musca convexifrons and Musca hervei, the former was thought to be an adequate vector of Thelazia rhodesi, because the species of Thelazia found in cows in Hokkaido and on Miyake Island was mostly T. rhodesi. The latter was found to be a vector of both T. skrjabini and T. rhodesi, because these Thelazia species were isolated in comparable numbers from the cows at Oume. 3. It was assumed that the development of the thelazian larvae in flies was different by the species of the host, for the body length of the infective larvae of Thelazia at full development was larger in Musca convexifrons than in Musca hervei.

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1. A seasonal prevalence of the horse-flies attacking cattles was investigated in the Kouzu pasture, Gumma prefecture for the year 1944 to 1946. About 50 cows of the Jersey race had been bred in that time in this pasture which was opened on the highland over 1000 meters level. 2. As shown in Table 1, twenty-nine species were collected in this pasture during three seasons. Among them, however, Stonemyia yezoensis, Chrysops basalis, C. suavis, Hybomitra arpadi, H. jersey, Atylotus horuathi, Tabanus miyajima, T. kinoshitai and T. iyoensis were very rare. Hybomitra jersey, Tabanus monomiensis and Chrysozona kouzuensis are the species which were described newly from this pasture as the type locality. 3. In each month from May to September, through three seasons, 4, 14, 25, 18 and 10 species were collected respectively. The largest numbers of species and of individuals were obtained in July, ined in second largest numbers of those were obta-and the August. 4. As is seen in Table 2, the result of quantitative evaluation of prevalence carried out in 1946 showed that Tabanus humilis was the most dominant species in number and Chrysozona rufipennis was next to this. Tabanus chrysurus, T. rufidens, T. fulvimedioides, T. amaenus, T. mandarinus and Chrysops japonicus were able to add further to the dominant species in which more than 50 individuals were collected. The activity of the horse-flies attacking cattles was largely affected by weather condition. 5. As shown in Table 4, the relation between the number of species and the number of individuals per species collected in a season was well described by Fisher's logarithmic distribution or by Preston's truncated discrete lognormal distribution as well. Intermediate steps for computing the statistics for both distributions were given in Table 3. From the result of application of the lognormal model, the estimated number of species that had not been captured was 11.39, it could be said that there is a possibility of finding some more species in the Kouzu pasture.

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For the purpose of clarifying the life cycle, development and some other ecological features of Parasa consocia Walker, and also in order to establish the relationship of moth-dermatitis and this species of moth, this study was conducted from 1965 to 1966. The results are summarized below : 1) In general, emergence of the adult moth is observed once a year, in June, in Kagawa and Tokushima Prefectures, although a small number of individuals also emerge in autumn. 2) Hibernation of this species of moth occurs when the advanced larva is in the cocoon. 3) Developmental periods occupy : 4 days, in the egg; 37 days, in the larva (until cocoon formation); and on the average of 300 days, in the cocoon. But, for the small number of individuals that emerge in the autumn, the duration is about 40 days. 4) Eight instars are observed in the larval stage, but a small number of individuals appear to have nine instars. 5) The growth in the width of the larval headcapsule follows Dyar's formula, log y=a+bx. 6) The number of eggs per egg-mass is variable, and the average is very small, about 5-6 eggs. 7) Strong aggregative behavior is generally observed in the first instar larva. However, dispersal seems to occur in the second instar. 8) Cocoon formation takes place on the lower parts of the trunks of old hackberry trees, or in nearby places; cocoons can be found in cracks in the bark on the trunk, or in weeds near the roots, in a cocoon-mass of variable size. The surface of the cocoon is quite indistinct and wrapped in a rather coarse silk. 9) The cause of dermatitis in the human body seems due to a large number of spine on the old larval skin, adhering either to the coarse silk on the surface of the cocoon or scattered on the ground. Undoubtedly, there is some suffering caused by the sting from spines on the living larva.

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The authors had an opportunity of examining rats and mice captured in the Yawata Iron and Steel Works during the period from September to October 1963 and in March 1964. The operations were carried out with cage traps and rodenticide "Kumaran" (coumarin derivative). The rats and mice were separately gathered at each site of the capture and preserved in 10% formalin. In the present paper, they reported on the species of rats and mice, the micro-habitats, the reproductive status and the measurements of external charactors of adult Rattus rattus. The results are summarized as follows : 1. The total number of rats and mice captured in autumn 1963 was 214 individuals, out of them R. rattus being 198 (92.2%), Rattus norvegicus 15 (7.0%) and Mus molossinus 1 (0.5%). In spring 1964, the total number of captured rats and mice was 101 individuals, R. rattus being 75 (74.1%), R. norvegicus 10 (10.0%) and M. molossinus 16 (15.9%). It is noticeable that the number of M. molossinus caught in spring is more than that in autumn. 2. In autumn numerous individuals of rats and mice were caught at resting room and the number captured decreased in order of office room and kitchen. In spring, however, R. rattus and M. molossinus were numerously captured at guardroom, resting room and dressing room. R. norvegicus was mostly caught at dumping place. 3. The bulk of female rats and mice captured in autumn and spring was oestrous, pregnant and lactating, and in the bulk of males the testes descended into the scrota. Therefore, the both females and males of R. rattus, R. norvegicus and M. molossinus were fecund in autumn and spring. 4. In R. rattus (♀53, ♂49), the average head and body length of adult females was 147.26±15.17mm; and that of males 149.45±10.08mm. The average tail length of females was 167.31±17.27mm; and that of males 163.45±15.46mm. The average hind foot length of females was 29.89±1.59mm; and that of males 30.59±2.02mm. The average ear length of females was 19.98±1.68mm; and that of males 20.18±1.37mm.

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The rats and rat-fleas were studied in the harbor side area of Yokohama and Kawasaki ports during the period from 1952 to 1965. Captivity of Rattus norvegicus has been increasing since 1955 and its rate among captured rats became over 75 per cent in recent years. On the contrary, Rattus rattus reduced its captivity after 1955 when its capture rate was highest, 55 per cent, and is below 25 per cent in recent years. Number of fleas collected has been gradually reduced after 1959. Number of Xenopsylla cheopis showed a peak in 1954, has been abruptly reduced, remained 1 specimen in 1962 and disappeared thereafter. Nosopsyllus fasciatus had been increased its number till 1955 and similar number has been collected thereafter. Monopsyllus anisus showed its maximum captivity in 1959, reduced enormously thereafter and no specimen was collected each in 1961 and 1965.

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From 278 overseas cargo ships fumigated with cyanogas, rats were found in an average of 10.8 per a vessel. The species and each rate to total rats were as follows : M. musculus 76.0%, R. rattus 23.3% and R. norvegicus 0.5%. The holds of vessels were most densely occupied by rodents with the rate 81.2% to total number, and the accomodation areas with a rate, 17.4% were secondarily invaded. In recent years, it is noticed that M. musculus becomes most abundantly invading vessels and the species was found from 46% of the vessels positive with rats. Invasion of rats was compared among different lines and nationalities. The invasion was measured by an average number of rats in a ship in each group. The highest invasion was seen in the south-east Asia service and in the Taiwan, Australia and India-Pakistan lines. Among nationalities, the highest was Norway, then Indonesia, Panama and Japan. Attention should be payed to the ships on those lines and in nationalities for preventing invasion of the foreign rat-born diseases.

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Xenopsylla cheopis was found from 5 overseas cargo ships out of 45 at Yokohama Port in 1966. Captured rats were 1, 099 and 64 X. cheopis were collected. The ships positive with X. cheopis were all on the Asian line and showed the positive rate 18.5% out of 27 ships on the same line. X. cheopis parasitized abandantly on M. musculus as much as on R. rattus and distributed in the various sections of the ships.

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Nous avons etudie l'influence des agents synergiques sue la vitsse de Knock-down de la mouche adulte en les melangeant a Allethrin et a Phthalthrin en proportion de 1 : 1, 1 : 3, 1 : 5, 1 : 10, 1 : 20, et 1 : 40. Les 6 agents synergiques utilisas au ces essais sont P. butoxide, S-421, Safroxan, Sulfoxide, n-Propyl isome, MGK-264, sous forme d' aerosol, selon le moyen de l'appareil 0.5m^3, ainsi que, en dehors de celui-ci, on a opere l' application topique. En ce qui concerne l' effet en aerosol, S-421 a la synergie la plus puissante avec Allethrin, et ensuite P. butoxide. Or, quant a Phthalthrin, il n y a pas d'agents synergiques tres effectifs, mais S-421 est le plus propre. On a comstate que : 1) La proportion de melange qui accelere le plus l'effet de Knock-down, c'est celle de 1 : 5. 2) II est inutile de meler au-dessus de 1 : 5. 3) D'ailleurs on n'a pas observe la tendance de l'augmentation de la mortalite parallelement a celle de doses de l' agent synergique.

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Laboratory tests on the effects of eleven insecticides against two colonies of the housefly, Musca domestica vicina Macquart collected from Kajiki of Kagoshima Prefecture in November of 1966, were carried out by topical application method, contact method to insecticide residues, spraying method and dipping method in laboratory. Insecticides used were as follows : dichlorvos, naled, diazinon, fenchlorphos, fenthion, fenitrothion, trichlorphon, malathion, dieldrin, lindane and DDT. Mortality after contact to the residues was higher in naled, diazinon, fenchlorphos, fenthion and fenitrothion. The others were less effective. Mortality in the spray tests was higher in dichlorvos, naled, diazinon, fenchlorphos, fenthion and fenitrothion ; and the others were less effective. In contact tests and spray tests, dichlorvos, naled and diazinon were more rapid in knockdown than the others. Both colonies of the housefly used were presumed to be the mixture of susceptible and resistant populations to dieldrin and lindane after the results of dipping tests.

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A mature larva of a psychodid fly was recovered from the left eye of a 37 year old patient who was suffering from an irritative feeling of the eye. The larva was collected from water used to wash the eye of the patient, and was brought to the author for identification. The specimen was already at the mature stage and its digestive canal was clean. It was actively moving in water when first exmined by the author. It was transferred into a small glass vial on wet filter paper in order to recover the adult, but it died 2 days later without the pupation. The specimen was mounted in balsam medium for the detailed microscopical examination of the structure. The larva is 7mm long, body greyish white in general, and the head and siphon are dark brown. There are 3 plates on each of the abdominal terga VI and VII, 5 pairs of siphonal tufts and 4 valves on the siphon, which is slender and tapering. The specimen was identified as Psychoda alternata Say, 1824 from its morphological characters. This case is considered to be the first report on human ocular myiasis due to the psychodid larvae.

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Kerosene and xylene were compared as the solvent in diazinon emulsion with an impregnated paper method for two colonies of housefly adults. The efficacy of kerosene was proven to be far higher than that of xylene.

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