1. This is a report on the investigation of the seasonal and diurnal activities of Culex tritaeniorhynchus summorosus leaving a pig shed. This work was carried out at Natori City, Miyagi Prefecture in 1965. 2. Culex tritaeniorhynchus summorosus was abundantly collected with the pig baited trap and showed a high rate (73.3%) of engorgement. 3. The percent engorgement of the mosquito population were maintained at higher than 80 percent from late June to mid August and decreased abruptly after late August. While the partial engorged females appeared after late August. 4. The diurnal activity of the engorged females which leave a pig shed showed a pronounced peak at 04 : 00-05 : 00,but that of the unengorged females was not clear. And the diurnal changes of the percent engorgement were very similar at every season. The high rate of engorgement at dusk falls immediately in the range of 20-30% and after two or three hours increased steeply.

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Duration of larval growth in Culex tritaeniorhynchus summorosus was studied under various photoperiods and temperatures. The growth was delayed by the short photoperiod (10 hours per day) (Table 1). In 14 hours of light, which is longer than critical day-length for induction of diapause at 25℃ (Ito et al., 1968), the wing length of the females lengthened remarkably. But, the duration of the larval stage did not change notably, though it lengthened when the larvae were reared at day-length shorter than 12 hours of light (Fig. 1). Under the long day condition the relation between water temperature and developmental velocity in the larval stage was linear between 16.6 and 34.0℃. The developmental zero temperature and the thermal constant of the larval stage was calculated as 8.3℃, and 110.6 day degrees, respectively (Fig. 2). In water temperature of 37.5℃ only 0.5 per cent of the hatched larvae pupated and all larvae died at the first instar at 44.0℃ (Fig. 3).

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While the authors were engaged in studies on mosquitoes in relation to epidemiology of Japanese encephalitis in Okayama Prefecture, western Honshu, a large number of mosquito species belonging to the subgenus Barraudius, genus Culex were collected. By comparative studies with the known species of the subgenus, the present species has been recognized most closely related to Culex (Barraudius) modestus Ficalbi, 1889; however, it differs in several morphological characters from those described by previous authors for the nominate form, especially in the structure of appendages on the subapical lobe of male genitalia. A new subspecies, Culex (Barraudius) modestus inatomii, is created, and its male, female, pupa and larva are described in this paper. The females of the present subspecies are voracious human biters. The immature stages were found in brackish water.

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During years 1971 to 1973,the following species of ticks, consisting of about 13,000 specimens, were recorded from the southern Amami-oshima Islands, mainly around Mt. Yuwan-dake : Amblyomma geoemydae, A. nitidum, A. testudinarium, Boophilus microplus, Dermacentor taiwanensis, Haemaphysalis campanulata, H. flava, H. formosensis, H. hystricis, H. megaspinosa, H. pentalagi, Ixodes granulatus, I. asanumai, and Ornithodoros sawaii. The prevalences of the predominant four species, A. testudinarium, H. formosensis, H. hystricis and D. taiwanensis, might primarily depend on the existence of the wild boar, Sus riukiuanus.

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The annual life cycle, and the seasonal and spatial changes in numbers and the age structure were investigated in a natural population of the smoky brown cockroach, Periplaneta fuliginosa S. Results obtained by the live trapping in a shed with regular intervals were as follows : 1. The largest number of cockroaches were captured in June. It seems to be due to the hatching of a vast number of nymphs and the high activity of cockroaches due to hot and humid weather in this month. 2. The seasonal change of the age structure indicated that the 'two-year life cycle' was normal in a natural population of the smoky brown cockroach, as Tsuji and Mizuno (1972) pointed out. The age structure in a overwintering population changes year to year partly because of this 'two-year life cycle', and the seasonal incidence of hatching, adult emergence etc. during successive active seasons may be roughly predictable from the age structure in the previous overwintering population. 3. The density and/or the instar composition were different from room to room and trap to trap, and these differences were clearer in young instar nymphs than old nymphs or adults. Assuming that the spatial differences in the number of insects being trapped reflects the spatial distribution in the shed, the distribution pattern was analysed by using the m^^^*-m^^^- relatioship method (Iwao, 1968). It was found that the distribution pattern was highly aggregative in all development stages. But this tendency was weakened in the following order : 1st-3rd instar nymph (β=8.0)>over 4th instar nymph (β=5.3-6.2)>adult (β=3.7). The degree of aggregation also changed seasonally. It was low in active seasons and high in inactive ones.

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1. The field survey on the tick had been made from May 1967 to the end of October 1972,at 33 points in 3 different Prefectures, Aomori, Iwate and Akita. In total of 1,005 mammals, 11 species belonging to 10 genera, were captured as the host of the tick (Table 1). A total of 584 specimens of ticks were collected from the above mammalian hosts. Ten species belonging to 2 genera and their hosts are shown in Table 2. 2. Two specimens of Ixodes sp. N1 obtained from Japanese shrew-mole were found as a new species. They have the similar features with I. persulcatus and I. sp. NB Ono, 1965. For comparison of morphological characters of these Ixodes species, I. sp. N1 may be easily distinguished from other 2 species in the shape of hypostome and scutum (Fig. 1). 3. Five human cases of tick biting were recorded from Aomori and Akita Prefectures in 1972 to 1973. In all cases, the removed ticks were identified as the adult female of Ixodes ovatus Neumann, 1899,which is widely and commonly parasitic on wild mammals in Tohoku (Fig. 2). Although there has been no record of this tick biting to man in Japan, and it is thought that there will be rather frequent opportunities to bite man in Tohoku area.

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An ecological study was made on the larval and imaginal population of Aedes albopictus (Skuse) in a cemetery of Nagoya City, central Japan, from April to November 1968. The present paper reports the larval and imaginal population dynamics from the view point of seasonal change of larval population size, larval age structure, imaginal population size and parous rate. 1) The number of mosquito larvae and pupae sampled from 3 stone basins by a bottom-screened dipper totalled, 2,182,of which 93.6% were Aedes albopictus (Skuse), 5.9% Culex pipiens pallens Coquillett and 0.5% Culex vorax Edwards. The number of adult mosquitoes captured with an aspirator was 532,of which 99.4% were A. albopictus and 0.6% Armigeres subalbatus (Coquillett). 2) Total number of A. albopictus larvae (pupae) in each stone basin was estimated by the application of the removal method (Fig. 1). To make a nearer approach to an understanding of population dynamics in the cemetery as a whole, the data of mosquito counts (x) were treated after being transformed into log (x+1), and the Williams' means were used for interpreting the seasonal changes of larval and imaginal population size. 3) The larval population occurred continuously from middle April to early November, and the population size reached its peaks three times (late April, middle July-early August, late August-middle September), of which the second peak was the largest. The imaginal population occurred from middle May to early November, and the population peaks were observed twice (late June-middle July, early to late September), the first peak being larger (Table 1 and Fig. 2). 4) It was indicated from the consecutive analysis of larval age structure that burst of adult emergence at population level seemed to occur five times (middle April-late May, middle June-early July, early July-late July, late July-late August, early Septmber-middle October) (Fig. 2). This estimation was certified by the mark-release-recapture method using Giemsa or carmine 1/1,000 solutions as marking dye (Fig. 4). 5) Each of imaginal population peaks were accompanied by the prominent increase of parous rate in early July to middle August and late September to middle October. Younger larvae appeared continuously and larval population size increased markedly around the first increase period of parous rate, but neither of such changes was observed in the second increase period (Fig. 2). This seems to indicate that eggs deposited in the second increase period of parous rate go through the winter and that the first larval generation of next year is derived from these overwintered eggs. 6) Discussion was given of the number of eggs hatching during a year in stone basins, remarkable effect given by grave-visitors on the mosquito population, and habitat segregation between A. albopictus and the allied species A. flavopictus.

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Extent of pale spots on the wings of Culex mimeticus and C. orientalis from Japan, and of C. neomimulus from Taiwan, together with their wing venation was studied to determine the diagnostic value of these morphological characters. It was found that some particular pale spots in the humeral and sectoral areas are definitely good characters for diagnosis of each species. The use of wing venation for the same purpose appears to be of limited value.

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Sterilizing effect of hempa was studied in relation to the ovarian development of the housefly, Musca domestica vicina Macquart. Continual treatment with low concentration of hempa below 0.02% to both sexes of the flies induced decline of hatchability of eggs laid during the treatment; decrease of egg production and complete sterility were observed by the treatment of high concentration above 0.1%. Flesh weight and follicle size of the ovary at 4 days after emergence decreased intensely by the treatment with the high concentration of hempa. Histological observations demonstrated that treatment with low concentration of hempa induced vacuolization of the ooplasm of the mature follicle, and that the high concentrations induced pycnosis and degradation of the nuclei of the nurse and follicular epithelial cells, collapse of the germarium and lack of the enlargement of the 2nd-follicles. Conspicuous vacuolization was also observed in the fat body of females. Histological changes described above indicate that the effect of hempa is, in addition to its known effect of inducing male sterility, concerned to induce sterility in female housefly.

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The descriptions of all stages of Androlaelaps himizu (Jameson, 1966) and Androlaelaps himehimizu sp. n. were given. The Japanese names, Himizu-togedani for the former and Himehimizu-togedani for the latter, were proposed. The two mites were thought to constitute a particular group, the A. himizu species-group, in the genus Androlaelaps.

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The survival and longevity of the male and female mosquitoes of Aedes togoi were observed by feeding on the flowers of 8 woody plants and the ripe persimmons in the same manner as described in previous reports (Harada et al., 1971,1972). The flowers of an oak (Lithocarpus edulis, Fagaceae) were most effective for survival of the mosquitoes among the tested, showing 98% survivals for both sexes on the 14th feeding day. Those of snowbell (Styrax japonica, Stryaceae) and spindletree (Euonymus sieboldianus, Celastraceae) were secondarily effective, showing 70% and 75% survivals for the males, and 80% and 60% for the females on the 19th day, respectively. Other woody plants, such as eldertree (Sambucus sieboldiana, Caprifoliaceae), bush honeysuckle (Weigela coraeensis, Caprifoliaceae), sumac (Rhus javanica, Anacardiaceae), dockmackie (Viburnum dilatatum, Caprifoliaceae) and azalea (Rhododendron indicum, Ericaceae) were also fairly effective for survival of mosquitoes. Whereas, the mosquitoes fed on the ripe persimmon, which contained 11.2% sugar, had the mean life spans of 12 days in the males and 18 days in the females. Especially, about 20% of the latter group survived over 40 days. These observations show that the nectar sources of the woody plants are very useful for mosquitoes to maintain their life. The nectar imbibed by the mosquitoes was detected on the 5th and 10th feeding days by the anthrone reaction according to Van Handel (1972). More than 90% of mosquitoes were positive in both sexes when they were kept for 10 days on the flowers of snowbell, chestnut tree, oak and sumac, and more than 50% were positive on milk vetch, rape, Japanese snowflower and sorrel vine. It is said from the results that the mosquitoes were active in nectar feeding than generally being thought. The blood-engorged females which had continuously been fed on various nectar flowers laid less numbers of eggs than those fed on 10% sugar solution did, 70.8 vs 182.6,in spite of the normal development of the ovarian follicles. The high sugar contents in the nectar flowers was possibly responsible for this.

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A common molecular size and shape was found among the attractive compounds when 124 alkyl carbonyl and few other types of compounds were studied for ovipositional attractancy of mosquitoes, Culex pipiens quinquefasciatus Say. The attractive compounds were mostly in 9-atom-length and branched. A methyl branch on α carbon or an ethyl branch on γ carbon from the functional group furnished attractancy, but those on β or δ carbons did inactivity with no exception. A methyl branch on ω-1 carbon furnished the best attractancy. Regardless the types of compounds; acids, ketones or esters, those in the similar contour showed the similar levels of attractancy. The 11-or more-atom-long compounds tended to be extremely repellent. All alcohols were inactive with one exception. The compounds in beyond 24-atom-length were inactive because of the involatility.

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Experiments were carried out to investigate the influence of different temperatures (27℃ and 15℃) on the behavioural interaction between two harbouring final instars and/or adults in each of four species of cockroaches, Periplaneta fuliginosa. P. americana, P. japonica, and Blattella germanica. Rectangular paper-pipes of 12cm×14cm×different heights (2cm, 1cm) or those of 3cm×2cm×different heights (1cm, 0.5cm) were used as harbourage shelters. These shelters were placed side by side in a test container and two insects of the same stage were released into the container. Each test was replicated eight or ten times. The results of the experiments can be summarized as follows. I. Periplaneta species : When tested at 27℃ with 1cm and 2cm shelters, adults, as well as final instar nymphs, tended to enter into separate shelters. At 15℃, however, they were usually found in couples in one of the two shelters, mostly in 1cm one. This suggests that the rejecting behaviour of Periplaneta species is suppressed through some mechanism under cooler conditions. II. Blattella germanica : More than 50% of adults were found in separate shelters or out of them irrespective of temperature conditions, suggesting that the harbouring behaviour of this species is different from that of the Periplaneta species.

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