The insecticidal activity of Dowco[○!R] 214,O, O-dimethyl O-(3,5,6-trichloro-2 pyridyl) phosphorothioate, against the common house fly, Musca domestica vicina Macq., was compared to certain public health insecticides under laboratory conditions of 25±1℃ and 60±5% R.H. The effectiveness of Dowco 214 from topical application, dry film contact and exposure to vapour was superior to that of fenitrothion. Excellent results were also obtained in the knockdown effectiveness using a settling mist apparatus, and on persistency with plywood panel tests. Dowco 214 is one of the most promising insecticides for controlling insects of public health importance because of its higher insecticidal activity, longer residual effectiveness and lower toxicity to mammals compared to other compounds being used.

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Evaluation tests of the insecticidal activity of a new organophosphorus insecticide, Dowco[○!R] 214,O, O-dimethyl O-(3,5,6-trichloro-2-pyridyl) phosphorothioate, against the mosquitoes, Aedes aegypti, Culex pipiens pallens and Anopheles sinensis were carried out under the laboratory condition of 25±1℃ and 60±5% R. H. The effectiveness of Dowco 214 to larvae and pupae evaluated by dipping test was superior to that of fenitrothion. By the settling mist method, the knockdown effect of Dowco 214 to adults of A. aegypti was excellent. Dowco 214 showed long residual effect to pupae in tap and filthy water. It is presumed that Dowco 214 is one of the promising insecticides for mosquito control.

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An experiment was carried out to observe the nutritional requirements of Dermatophagoides farinae for efficient breeding. The breeding mode of D. farinae with 27 kinds of diet was compared with the control, composed of equal amout of dried yeast and powdered fish, which has been used for maintaining the mites in our laboratory. Approximately 800 mites were inoculated on 20g of the above series of diet, and they were kept at 25℃ and 60% R.H. The mites in 0.5g of the culture media were counted every two weeks by the saturated saline floatation method. Higher reproduction was observed in four kinds of diet than control : (1) 5% of lard plus fatless control (the fats being extracted thereof, and 5% of lard being added) produced the highest count 9,930 in 18 weeks; (2) 5% salad-oil plus fatless control, 8,085 in 18 weeks; (3) dried yeast and bean-flour (1 : 1), 4,110 in 22 weeks : (4) driedyeast and egg-albumin (1 : 1), 2,935 in 22 weeks; while the control, 2,595 in 18 weeks. It is assumed that fats, especially animal fats in the diet, might contain some substance to meet nutritional requirement for this species. As source of protein any of powered fish, bean-flour, and egg-albumin was satisfactory to breed this species.

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It seems worth to record newly introduced cockroach species from faunal as well as pestcontrol point of view. During recent years the following three Blattellid species were found in our faunal limits. 1. Supella longipalpa (Fab.)(=spellectilium Serville) This well-known tropical pest was found in 1969 in the houses of Chichijima of the Bonin Islands. 2. Lobopterella dimidiatipes (Bolivar) This soil-surface cockroach has been known from many Pacific Islands. In Japanese territory it was first discovered by Prof. R. Kano in 1955 in Iriomote Island, the Yayeyama-group of the Ryukyus. Then, from the other Ryukyu Islands, i.e., Okinawa, Miyako, Ishigaki by my colleagues and myself. There are also specimens from Yang-ming-shan, near Taipei and Kuraru, southern Taiwan, the latter taken by Dr. Chu. 3. Imblattella panamae (Hebard) This is an indigenous Panamanian species. In recent years many individuals were detected from the pots of tropical orchids. In Tokyo area this cockroach is said to be not uncommon in the greenhouses where tropical orchids are cultivated, probably imported directly from Central America, or indirectly, from nurseries of orchids or tropical plants in the other part of the world. A brief description for each species were given together with illustrations of taxonomic characters.

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Aedes (Finlaya) savoryi Bohart, 1956 was described by the original author from eight females. In 1969 and in 1971,the present authors discovered its larvae and pupae in seaside rock-pools in Ogasawara (Bonin) Islands. The present paper deals with the descriptions of the male, pupa and larva of Aedes savoryi which heretofore were unknown. As pointed out by Bohart, females possessed characters of subgroup III, group H of subgenus Finlaya proposed by Knight & Marks (1952). But male genitalia of this species lacked the "tuft" of specialized scales, which was the key character of subgroup III. The pupa and larva of this species were similar in structure to those of Aedes togoi. The pupa of the former could be distinguished from that of the latter in that the paddle without spicules was provided with two apical hairs. In larva, the number of teeth on mental plate was from 21 to 25 in A. savcryi and from 29 to 37 in A. togoi. This species is indigenous to the Ogasawara (Bonin) Islands and breeds in the brackish water rock-pools only. The blood sucking activity was highest at sunset and sunrise, but attacked man during the day as well.

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Investigation of the fauna of medically important animals in the southern Amami-Island was done from September 1971,mainly around Mt. Yuwan, and the results of the (annual) investigation on trombiculid mites are presented here. 1. Unengorged larvae were mainly collected from the soil. 12 genera and 27 species were identified, among which 13 species have been known, while the others are considered to be new species. Descriptions of the new species are to be reported in another paper. 2. Genus Schoengastia which has not previously been reported from Japan, and many other species which destributed in South East Asia were found. 3. Existence of Leptotrombidium scutellare, the main vector species of Tsutsugamushi-disease on the Izu seven islands and in some parts of the main land of Japan, was found. 4. 7 genera, 18 species were found from the nest hole of Amami-hare, Pentalagus furnessi (Stone, 1900), the most important host of trombiculid mites. 5. Several species of trombiculid mites are considered to be specific parasites of Amami-hare. Most of the species of trombiculid mites were found at Mt. Yuwan, where primeval forests and the conservation of the natural environment protect Amami-hare and other small animals, which are hosts of these mites. 6. Four species of trombiculid mites, which had usually been found from birds, were collected from soil in the breeding habitats of sea birds.

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In this paper was reported the results of my survey on the medical insects, excluding flies, made chiefly in the Chichi-jima in the Ogasawara Islands (Bonin Islands) from August 1968 to October 1969. 1. Seven species of the mosquitoes were found to be distributed in Ogasawara Islands : Aedes savoryi, Aedes togoi, Aedes albopictus, Ades sp. I, Culex boninensis, Culex pipiens fatigans and Culex vorax. 2. Larvae and pupae of Aedes savoryi were collected from rock pool of sea coast at southern edge of Chichi-jima. Since the rearing of them in the laboratory were succeeded, the morphology of this species in immature stage and in male adult, which had been unknown, were observed. The blood sucking activity of females against men was also found to be very intensive outdoors in the day light. 3. Females of Aedes sp. I were caught by biting collections. But these in adult male or in immature stage were not found. 4. Among these seven species collected in this work three species of Aedes savoryi, Aedes sp. I and Culex boninensis which seemed to be peculiar to this Islands were quite unknown in epidemiologic significance. 5. In Chichi-jima Aedes albopictus were predominant in the thick forests and Culex pipiens fatigans in the proximity to human habitations. Both species, however, were not active in winter (January and February). 6. Aedes aegypti, known to have been distributed in large number in Ogasawara Islands, were not found at all during this work. 7. In Chichi-jima six species of the Cockroach were found. Blattella germanica, Blattella lituricollis, Onychostylus vilis, Periplaneta americana, Periplaneta australasiae and Supella supellectillium were collected in human houses, and two species of Blattella lituricollis and Pycnoscelus surinamensis in the field. In Iwo-jima Pycnoscelus surinamensis was collected in the field. 8. Blattella lituricollis were said to be found on the grass land around the human habitations. Only one specimens was collected coming to the light of a room at night. 9. Onychostylus vilis was the most abundant species as well as Periplaneta americana in the human houses of Chichi-jima. 10. Supella supellectillium was found first in our country. 11. In Chichi-jima Polyplax spinulosa was collected from Rattus rattus caught with alive-rattrap, and Ctenocephalides felis from dogs and cats. 12. Culicoides claggi Tokunaga, (1959) had already been recorded in the Island, but no specimen was found during the present work.

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The overcrowding factors of Chironomid larvae were proved in the cultures by breeding them in various numbers in a constant bottom area and in a constant number in various area. The factors delayed the midge emergence and decreased the emergence-rates significantly in both the factor-producing water and the conditioned water. The higher the larval density in the factor-producing phase, the more the midge emergence was delayed and dispersed. There were the linear regression between the logs of larval densities and the probits of emergence-rates in both factor-producing and bioassay phases. The production of growth-retarding and toxic factors was dependent on the larval density rather than the number of larvae in the culture.

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An ecological study was made on the larval population of Aedes albopictus (Skuse) in a cemetery of Nagoya City, central Japan, during a period from June to December, 1967. The present paper reports the larval population dynamics in natural habitat from the view point of seasonal change of population size and age structure. 1) The number of mosquito larvae and pupae sampled from 10 stone basins by a dipper totalled 2,090 during the study period. Most of them (97%) were A. albopictus, and the rest were Culex pipiens pallens, C. tritaeniorhynchus and C. orientalis in decreasing order. 2) Statistical analyses were made of the relationship between mean and variance of A. albopictus larval (pupal) counts in the 10 stations, and it was revealed that distribution of individuals seemed to be contagious and to fit well to the negative binomial distributions with a common k except a few cases (Figs. 3,4 and Table 2). The log(x+1) transformation was adopted in order to normalize the data (x : individual counts per stone basin) according to Bartlett (1947), and the Williams' means (Williams, 1937) were used to represent the seasonal change of population size and age structure of the larval population in the cemetery as a whole. 3) The larval population was observed from late June to late November, and the population size reached its peaks three time (early July, early August and early September), of which the peak in early August being the largest (Fig. 5). 4) Consecutive analysis of larval age structure indicated that adult emergence at population level seemed to occur about three times (late June-mid July, late July-early September, mid Septembermid October) roughly in parallel with the above-mentioned population peaks. Judging from the largest population size and continuous adult productivity in larval population, emerging adults were estimated to be most abundant at the second emergence period (Fig. 5). 5) There were appreciable differences in seasonal fluctuation pattern of the larval population size between the two representations : one was expressed by arithmetic mean of actual individual counts and the other by the Williams' mean (Fig. 5). So, a comparison was made between the arithmetic mean of actual individual numbers and that of log-transformed ones in regard to frequency distribution and variability of the observed counts. As a result, the log-transformed numbers seemed to be more suitable for analyzing dynamics of mosquito population in a habitat area as a whole, because the arithmetic means of the log-transformed numbers were more centrally located and the coefficients of variation of them were more minimized (Figs. 6,7).

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It has been reported in our previous studies that a fresh water fish of the family Poeciliidae, the guppy or Poecilia reticulata (Peters), has established in a number of areas in Asia after being introduced from South America as a pet fish, and served as an efficient predator of mosquito larvae in sewage waters. The fish was found also to be highly adapted for breeding in polluted waters and effective in cleaning organic matters and microoganisms. In this connection, studies were made on the tolerance of the guppies to the septic pollution of water and for identification of the cause of the toxicity. When 5g of the powder of laboratory animal food is added to 10 liters of water and kept at 23℃, the dissolved oxygen in water becomes undetectable within several hours; the guppies, however, released in such water can survive many days apparently by taking oxygen from the water surface. The absence of dissolved oxygen is therefore not the direct cause of the death of the guppies, though it may be fatal to other fish species. When larger amounts of the septic substance is added to water, such as over 10g of the animal food into 10 liters of water, the water becomes toxic to the guppies after about 4 days, and the toxicity lasts for about a week. However, the guppies exposed to the water before and after such a toxic period stays apparently healthy, though the dissolved oxygen may be undetectable. Interestingly enough, the guppies which survive keep on eating the fouling substances and the microorganisms, and eventually the water recovers its oxygen content after most of the organic matter is consumed by the guppies. The toxicity of septic waters to the guppies was found to be highly correlated with the concentration of H_2S in water. The water becomes fatal to the fishes from about the fourth day when the H_2S concentration increases to over 1ppm, and remains so for about a week until the concentration drops again to below 2ppm. The pH level during this period is usually below 6,but it gradually changes to near neutral in connection with the increase of NH_3 in the water. The septic water also becomes non-toxic to the fishes after providing aeration for a few hours. Under experimental conditions, H_2S dissolved in distilled water exhibits toxicity to the fishes at concentrations higher than 1ppm, while the toxicity of ammonia in water is seen at concentrations above 11ppm. It was also observed that the toxicity of H_2S and NH_3 is remarkably reduced by mixing the two solutions at adecuate ratios. The solution of (NH_4)_2S is safe to the fishes even at 63ppm, and becomes toxic only at concentrations 125ppm and higher. It is presumed that the accumulation of H_2S produced by microorganisms under anaerobic condition is the principal cause of the toxicity, and subsequent increase of ammonia in water acts as a neutralizing agent. It was further observed that the toxicity to the fishes could be easily minimized by providing aeration into the septic waters in connection with the recovery of dissolved oxygen. The D.O. concentration of the septic water rapidly increases after commencement of the aeration, but in most cases the concentration starts to drop after several hours, probably the result of the reproduction of aerobic microorganisms which consume oxygen for oxidizing the fouling substances. The secondary increase of D.O. concentration occurs some time later, after most of the septic substances are saturated with oxygen.

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The onchocerciasis is one of the most important diseases of human in Ethiopia. From the epidemiological point of view there is apparently much remained to be investigated on the ecology of the vector, the black flies. In this study the biting habit of the black fly, Simulium damnosum, against man was observed particularly on the diurnal fluctuation of the biting activity. The biting collections were carried out in two types of places, namely the sunny places and the shady places. It was noticed that in the sunny places the flies began to come attacking man with the rise in temperature and illumination intensity in the morning but then the number of flies decreased according to the sudden increase in the intensity of illumination. So there appeared a peak in the activity around 9 : 00 hours a.m. There was also a peak observed in the afternoon at about 5 : 00p.m. It can be concluded that the biting activity of this fly has a bipeaked fluctuation picture in the daytime, one peak in the morning and another in the afternoon. However in the shady places where no remarkable fluctuation in the illumination intensity occurred no obvious peaks in the activity could be observed.

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The survey on the thelazian parasites and their intermediate hosts was made in the farm of National Institute of Animal Industry in Chiba city from January 1972 to May 1973. Four genera and 6 species, totalling 9,097 flies were obtained from cattle bodies and Musca hervei was dominant (63%). Among the collected flies, some of Musca hervei and Musca bezzii were infected with thelazian larvae, and 93% of them were females of M. hervei. Interest result of this survey was a discovery of thelazian larvae in males of M. hervei. Krastin (1950) supposed that the larvae invade into the follicle of ovary and develope therein. However, Vilagiova (1962) found larvae of T. gulosa in fat tissue of male and ovarian follicle of female in M. autumnalis and supposed the similar relationship also in T. rhodesi and T. skrjabini. The authors could not observe the larvae in the follicles, but found tunicate larvae adhering to the wall of body cavity in both sexes of M. hervei. On the origin of this tunica is a problem in future. Month of maximum infected rate both in the flies and cattle eyes was October. The transmission of thelazian larvae to the eyes of cows by flies was continued from spring until late fall. Adult parasites are kept in the eyes of cows during the winter and new infection of larvae to the flies begins at the same time with emerging of the overwintered flies. New infection of infectious larvae to the eyes of cows begins in the middle of May, because newly infected larvae from cows to flies in early spring take more than 50 days to develope to the infectious larvae.

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