Four species of bat-fleas from Hokkaido and their hosts are studied. They are Nycteridopsylla nipopo from Murina aurata ussuriensis, Ischnopsyllus (Ischnopsyllus) elongatus from Noctula lasiopterus aviator, Ischnopsyllus (Ischnopsyllus) obscurus from Vespertilio superans, and Ischnopsyllus (Ischnopsyllus) needhami from Vespertilio superans. The occurence of I. obscurus in the north-eastern part of Hokkaido is recorded here for the first time.

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In order to investigate the relationship between calendar age of mosquitoes and physiological age determined by the observations of ovarioles after Detinova (1962) the examinations were carried out at 25°C and 80-90% RH conditions with the colonies of Culex pipiens pallens which have been collected in Tokyo and maintaned in this laboratory. The results showed that by 24 hours after emergence the follicles developed from N stage by Detinova to the stage I by Christophers. The follicles remained to I stage unless the mosquito fed on blood meals, however they continued to grow and the diameter reached to around 80 microns on three days after the emergence then kept almost same size until blood feeding. By three days after emergence over the half number of female mosquitoes took the blood meals and after six days over 90% were observed to finish blood feeding and also mating, which was determined by the presence of sperms in the spermatheca. After engorgement the follicles started to develop; by three days they reached to V stage and the longer diameter grew from around 100 microns up to about 550-600 microns. However the actual ovipositions took place a little later, and it was six days after engorgement that more than half of examined mosquitoes had been found to lay eggs. In twenty four hours after oviposition the saclike dilatations formed at ovariole pedicels completed their contraction and made the relics, therefore a considerable part of mosquitoes which were obtained in the field and found to have one relic per ovariole, that is, determined of one physiological age, could be considered to have elapsed around ten days after emergence. The mosquitoes which finished the oviposition were found to refeed on animals in a remarkablly short period after laying eggs; by 15 hours after oviposition more than half of the mosquitoes were observed to reengorge still having sac-like dilatations in ovaries. Whereas the period required to make the second oviposition could be considered to be almost the same with that in the first gonotrophis cycle, the second egg-laying would occur around 16 to 17 days after the emergence of the mosquito. So the physiological age of two would correspond to around 16-17 days of calendar age in the majority of mosquitoes.

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One year observation on the fluctuation of population density of Culex pipiens pallens was carried out in a large cave and in the chicken houses outside of the cave located in the vicinity of Tokyo, from Feburuary of 1963 to Feburuary of 1964. Physiological age was also determined with each collected specimens in accordance with Detinova's method and seasonal changes of age composition of the population were observed. The data on the density combined with those on age composition facilitated the dynamic analysis of natural population of mosquitoes. Five phases were distinguished concerning to activity of mosquito population on the basis of changes in density and age composition; that is, hibernating phase in winter, reactivated phase in the early spring, first generation in spring, proliferating phase in summer, and pre-hibernating phases in autumn. The parous rate of population which is hibernating in the cave was observed constantly at the level of around six or seven per centage. Although all of the parous mosquitoes of hibernating population were found to have only one relic at ovariolar pedicles, the fact indicated that at least a part of hibernating mosquitoes did take a blood meal before entering into hibernation. This would be of interest pertaining to possibility of overwintering of some arthropod-born viruses by adult females of hibernating mosquitoes. The temporal decrease of population density was observed to take place in the midst of summer season. The slight aging tendency which was concurrently noticed in the age composition of adult population of this season suggests that decrease of number of adults could be resulted from decrease of pipiens larvae by their natural enemy, i. g. the larvae of Culex vorax which is well known to breed in breeding places of pipiens larvae in that season. The developing stage of follicles in ovaries were found all remaining at Christophers's I stage in mosquitoes which were hibernating in the cave, however, the most parts of mosquitoes in active seasons were observed to have the follicles at II or III stage. As the latter specimens of mosquito were collected inside of the chicken houses at around three o'clock in the afternoon, and the majority of them were shown to have blood clot in stomach, it may be natural that the follicles had developed to some extent by that time after engorgement. However as it was reported in the previous paper of this series, the period required for the follicles to develop up to II or III stage would be about 24 hours at 25℃, a fact suggested that mosquitoes remained for a considerable period in chicken houses after taking a blood meal.

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In the previous paper, the author reported on the differences in activities of various enzymes in the body of typroglyphoid mites, and that remarkable differences by the species were seen those which acted on carbohydrates. The present study was intended to see mode of utilizations of various carbohydrates as nutrients by different species of the grain mites as observed from the rates of reproductions in food composed of mixtures of dried yeast and various carbohydrates. Cultures of three species of the grain mites, Tyrophagus dimidiatus, Aleuroglyphus ovatus and Carpoglyphus lactis were made in media composed of the mixtures of dried yeast and carbohydrates (glucose, lactose, sucrose, dextrin and starch) at the ratios of 10 : 0, 8 : 2, 6 : 4, 4 : 6, 2 : 8 and 0 : 10. They were kept in separate containers regulated at relative humidity of 75% in an incubator at 25℃. The densities of mites in the cultures were counted at two weeks intervals. Carpoglyphus was found to breed best in the media containing 40 to 60% glucose or sucrose, while the diets containing dextrine and starch were less adequate as food than dried yeast alone. On the other hand, the rate of reproductions of Aleuroglyphus ovatus was the highest in cultures composed of the mixtures of starch and yeast at about equal ratios. However, the mite was estimated to be unable to utilize glucose and lactose for its reproduction. Tyrophagus was found to be intermediate type in its nutritional requirements between the above two species, and the addition of any of the carbohydrates to the yeast was had the effects to increase its rates of reproductions. The results shown above seem to indicate that Caropoglyphus lactis is the mite that utilize glucose or sucrose as the nutrients but not the starch, while Aleuroglyphus is the reverse in its requirements, and that Tyrophagus has broader allowances and can utilize a variety of carbohydrates from glucose to starch.

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The breeding places and some habits of tabanid flies concerning with their control were investigated in the mountainous regions of Yamagata and Niigata Prefectures in 1964. The results were as follows : 1. The larvae of Tabanus iyoensis, adults of which are prevalent in the mountainous regions, were found beneath decayed leaves lied thick on bushy ground. 2. The larvae of T. sapporoensis were also collected beneath decayed leaves lied on somewhat watery places. 3. Some knowledges concerning with the breeding places of mountainous tabanids such as Chrysozona rufipennis, Tabanus chrysurus, Silvius matsumurai, etc. were also obtained. 4. Most (93%) of the tabanid larvae collected from rice fields were identified with those of Tabanus mandarinus, and others were those of T. takasagoensis, Chrysops van-der-wulpi and an unidentified species. 5. No larvae of bloods sucking tabanids were obtained from sandy soil of river-bank. 6. Tabanid larvae fed on earthworms, Limnodrilus gotoi and Pheretima communissima. 7. Some types of seasonal occurrence were recognized : Chrysops japonicus appeared late in April and vanished early in May, Tabanus fulvimedioides appeared late in June and vanished about the middle of July when many other tabanids began to come out, and Chrysops basalis appeared late in August when the tabanid occurrence declined. Most of tabanids appeared in midsummer, while the occurrence of Chrysops van-der-wulpi and Tabanus amaenus were thought to last long from late in May to the end of August. 8. The tabanids which occurred before the midsummer were thought to appear later and those which occurred after the midsummer earlier in mountains than those on plains, therefore the duration of tabanid occurrence in mountains was observed to be shorter than that on plains. 9. Peaks of occurrence of T. iyoensis, T. mandarinus and T. trigonus were seen at the middle of August. 10. The duration of occurrence of T. iyoensis at the upper stream of Tamagawa River, Yamagata Prefecture, was about a month from late in July to late in August. More than 90% of tabanids collected at their most prevalent period of the middle of August were occupied by T. iyoensis. 11. Most of T. iyoensis were observed to attack cattle and men in the early evening (6.00〜7.00P.m.). 12. T. iyoensis and some other species were observed to be attracted by carbonic acid gas originated from dry ice. 13. Some of T. iyoensis and T. sapporoensis were observed to be attracted by a fluorescent lamp. 14. The cow applied with the repellent (main element : Dimethylphthalate) on body surface was prevented from attack of tabanids.

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During a period from April, 1962, to February, 1963, the prevalence of Culex mosquitoes which breed in the septic tanks for water closet located within the city of Tokyo, Shibuya, Harajuku and Yoyogi, was investigated. Similar observation was made from April 1963 to June 1964 at the same tank of Harajuku. At the septic tank of Shibuya the mosquito was recognized, in 1962, from the beginning of July until December, at Harajuku from the middle of June until January of 1963. During 1963 the mosquito population declined at Harajuku, appearing in late June, disappearing in early December. This is probably due to netting at the opening of disinfection tank. It was demonstrated that in the early season (June-early August) the tank of Shibuya was occupied by Culex pipiens pallens, then, in August, both C. pipiens pallens and C. molestus coexisted, but in September the latter species monopolized and finally the both are mixed again from late October to middle November. At Harajuku the tank was occupied by C. pipiens pallens until late August, which was followed by the mixed population during September but C. molestus remained exclusively later then. Similar phenomenon was seen in 1963, i. e., C. pipiens pallens occupied from July to early September, both species from middle September to early October, then only C. molestus remained. At a septic tank of Yoyogi netting at the exhaust pipe and blocking of manhole crevices, accompanied with insecticide spraying into the second septic tank, completely prevented the mosquito annoyance.

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The autogenous mosquito, Culex molestus, usually invades into septic tanks for water closet and establishes themselves not only in its disinfection tank but even in the second septic tank. A series of the tests was conducted to kill mosquito larvae without interfering decomposing process of microorganisms breeding in the aerobic bed. It was observed that the application of diazinon emulsion in 5ppm, or malathion in 5ppm affects unfavourably to the total population of microorganisms and their balanced composition. On the other hand malathion in 1ppm, Baytex in 0.25ppm did not show any recognizable influence upon microorganisms. A laboratory as well as a field test were conducted in order to check the efficiency of used insecticides. In laboratory tests using, as the diluent, chlorine free tap-water or actual septic-tank water, Baytex (fenthion) and Sumithion (fenitrothion) showed high efficiency to the mosquito larvae which belong a high DDT-resistant strain. In field tests, the mosquito larvae kept in a cage were submerged in septic-tank water. When Baytex or Sumithion, in 0.25ppm respectively, was applied 100% mortality of the caged larvae was recognized after 24 hours. On the other hand, diazinon application has shown 99% mortality in 1ppm, but only 50% in 0.5ppm. Against the adult mosquitoes prevailing in the closed space of a septic tank a 20% DDVP resin strip has given a promising effect.

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