In order to investigate the behaviour pattern of feeding of three species of cockroaches, some preliminary experiments were carried out on their responses to olfactory and gustatory stimuli of food origin. The responses of the three species to the constituents of rice bran and some carbohydrates clearly indicate that the chemical basis of their food preference can be classified under four headings; (1) volatile substances which are soluble in n-hexane and act as olfactory attractants, (2) methanol-or water-soluble and (3) n-hexanesoluble substances which act as feeding stimulants, and (4) sugars and related compounds also acting as gustatory feeding stimulants. There is the lack of specificity of some feeding stimulants such as maltose, L-arabinose, sorbitol, fructose and sucrose among the three species. It is likely that there is the lack of specificity of n-hexane soluble releaser substances among them. The effects of galactose and mannitol, however, are somewhat or highly species-specific in the three species, and there are different responses to the acidic fraction A of the n-hexane soluble extract of rice bran between B. germanica and the other two species. There are also different responses to the n-hexane extract S_1 and to the acidic fraction A between the newly hatched nymphs and adults in P. americana.

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1. Investigation of the altitudinal distribution of flies was made on the Mt. Fuji from 28th to 30th of July, 1964. 2. Eight collecting stations were selected, where flies were gathered with 2 cage traps uaing horse minced flesh as the bait. 3. Collected flies were identified and counted. The results were shown in figures and in a table. 4. Each fly species had its own distributional range, which was determined chiefly by climate, flora and the presence of the breeding place, particularly human dwellings. 5. There were 4 altitudinal zones of fly distribution : (1) 0-500m. (2) 500-1, 500m. (3) 1, 500-2, 500m. (4) Over 2, 500m.

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An investigation of bovine thelaziasis and its vectors was conducted on Miyake Island, Tokyo, during the period of September 16th-23rd, 1963. The results are as follows : 1. Adults of Thelazia species collected from the eyes of the cows were mostly T. rhodesi, and a few specimens of T. skrjabini was also captured. 2. Twelve cows were examined and they were all infected with Thelazia. Some of them were infected with both T. rhodesi and T. skrjabini. 3. The flies found on the cows were mainly Musca convexifrons and Morellia simplicissima. 4. Seventy one males and 1, 310 females of Musca convexifrons were dissected, and 7 females were infected with thelazian larvae. These thelazian larvae were identified as Thelazia rhodesi. Twenty five males and 179 females of Morellia simplicissima were dissected, but no thelazian larvae were found from them. 5. Infection rate showed a direct correlation with ovarial development in M. convexifrons. The highest infection rate was found among the flies with fully developed ovaries. 6. The vectors of Thelazia rhodesi were females of M. convexifrons. The vectors of Thelazia skrjabini were not found in this survey, but females of M. convexifrons were estimated to be the vectors.

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The distribution pattern of the larvae of the predatory mosquito, Culex (Lutzia) vorax in a ditch was analyzed by the index of aggregation (Iδ, Morisita, 1959). The aggregation of the larvae of C. vorax was comprised of two groups with different size. Smaller aggregation was about 10cm in width and the other was dispersing over a range of about 2m including some of the former in it. The larger group was considered to be consisted of the larvae dispersing from one egg raft. The C. vorax population was, therefore, considered to be intermingled with the population of the prey, C. pipiens fatigans, not individually but as a group. Consequently, the heaviest reduction of the prey population was found in the areas where C. vorax is occurring. The larvae dispersed quickly after hatching in the laboratory but ceased to spread after 24 hours when almost all the larvae had attained to the second instar. The distribution pattern, however, was still aggregative after the stabilization. The relationship between the prey population and the quantity of the predation was recognized as Ivlev's (1961) predation curve, fitting the formula r=R(1-e^<ξN>). As for first instar larvae, however, the expected values obtained by this formula hardly fitted to the observed ones. Those values calculated by the following formula, r=R{1-e^<ξ(N-a)>} fitted quite closely to the observation. The asymptote obtained here was lower in the more advanced instar. On the other hand, the first instar larvae had higher predatory efficiency, and fed on more larvae at higher density of prey population and this higher predatory efficiency differed discontinuously from those of the second and later instars. Such a higher predatory efficiency in the first instar seemed to cause the faster growth of the larvae within the instar. This phenomenon was recognized by the growth curve of this species in the formula, Y=5/(1+e^<-0.579(x-1.702)>). The cannibalism of C. vorax was examined experimentally. Four fourth instar larvae of both prey and predator were released into a vial and the reduction of individuals of each species was counted in time sequence. The reduction of the number of the prey larvae always occurred first, but the cannibalism among individuals of the predator larvae did not occur when a certain number of prey larvae was present. This phenomenon seemed to be attributed to the specific behaviour of the predator such as settling and waiting to capture prey even if no prey was present. The settling behaviour of the predators was apparently reducing the chance of the contact among themselves, therefore, the cannibalism did not occur when the prey, which moves more frequently, was present.

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Crossing experiments were carried out between Gr and Ka strains of Culex pipiens s. l. with different genetical characters, the former representing autogenous or molestus-form associated with greencoloured larval mutants, and the latter being anautogenous pallens-form with normally coloured larvae. F_1 eggs obtained by the crossing between Ka-females and Gr-males showed only 1.8% of hatching rate, the rest 53.1% harboured embryos which were matured but unhatched, and 45.1% were unfertilized. The above rates for F_1 eggs of the cross between Gr-females were 0.1%, 36.8%, and 63.1% respectively. The sex ratio of the former cross was roughly 1 : 1 but all the adults recovered by the latter were females. The hatching rate of F_1 hybrids of the former was almost as high as that of the parent colonies. Gr was selected from a colony of molestus n nature and has been established as a homozygous green larval strain. In the former crosses phenotype of F_1 larval were all "green". Larvae of F_2 were composed of 20.6% of green, 19.6% of normal and 60.4% of intermediate. It was estimated from the above results that the green character is polyfactorial in its inheritance. Among the females obtained by the former crosses, the autogeny rate was 6.7% at F_1 and 3.8% at F_2. No correlation was observed between the apearances of larval colour types and the autogeny of the females.

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It is anticipated that the effect of fly-maggots larvicide is influenced by the absolute volume of the used diluent under "the dilution contact method", in which the test insects are exposed to a certain depth of, or a thin layer of, insecticide dilution for 48 hours and mortality counts are made. The relationship between the used volume of lindane emulsion at the various concentrations and the LC-50 value was investigated using last inster larvae of the flesh fly, Boettecherisca peregrina (Rovineau-Desvoidy), in a test cotainer of 9cm diameter and 6cm in height. The volume of the each diluent was 1, 2, 4, 8 and 16ml, respectively. Through this investigation, it was experimentally confirmed that the relationship between the volume of the used diluent and the LC-50 value showed an inverse correlation as a single straight line. In any series of the experiments, 4ml application has given the most stable LC-50 value. The absolute amount of the active ingredient will be expressed as an index which is obtained by the product of the volume of diluent at each dilution and the concentration. Experiments showed that the more the volume of diluent at each dilution was used, the more the mortality was determined even when the index value was constant. It seems to be influenced by the additional drowning effect. On the contrary, in case of the 1ml application the mortality decidedly decreases. An explanation of this phenomenon will be reported elsewhere.

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A series of experiments was made with larvae of Culex pipiens s. l., to determine factors influencing the effects of larvicides under different water conditions. DDVP, diazinon, ronnel, lindane, malathion, Sumithion, Baytex, dieldrin and p, p'-DDT were used as the larvicides. The fourth instar larvae were exposed to various concentrations of the larvicides in water for different periods of time, ranging from 1 minute to 24 hours. The results showed that in order to obtain the same mortalities in one-tenth the exposure time, it was necessary to increase the amount of toxicants about 10 fold. This relationship between exposure and the amount of toxicants was applicable to most of the larvicides tested, with a few exceptions in cases of some concentrations of lindane or dieldrin. Under the stable water conditions effectiveness of the larvicides was reduced by adding organic materials which absorbed the toxicants. However, the addition of either non-absorbable or water-soluble materials such as starch or sugar did not appear to influence the effects of the larvicides. The absorption of the toxicants into the organic materials appeared to contribute to the reduction of the effects. The quantities of the toxicants which were absorbed into the compound were greatest in DDT and dieldrin, with the following descending order : Baytex, Sumithion, ronnel and diazinon. The absorption of DDVP was not evident in all the compounds tested which is free from active carbon. Active carbon absorbed large amounts of the toxicants in comparison with the others. Three grams of the absorptive materials were added to 100ml of water containing 2ppm of the toxicants, and maintained under sterilized condition for 4 days at 25℃. Results were as follows, with the quantity absorbed given in brackets. Filter paper-DDVP (7.5%), -diazinon (9.0%), -Sumithion (26.5%), -Baytex (36.5%) and -DDT (87.5%). Wood chips- DDVP (19.5%), -diazinon (81.0%), -Sumithion (79.5%), -Baytex (86.0%) and -DDT (92.5%). Larval diet (standard laboratory animal pellets) -DDVP (25.5%), -diazion (75.0%), -Sumithion (86.0%), -Baytex (86.0%) and -DDT (96.0%). From the results of this experiment, it has been found that the descending order of the absorption to the materials was as follows : active cabron > larval diet, wood chips > soil > filter paper > talc, kaolinum, bentonite. There was little absorption of most toxicants by starch or diatomaceous earth. Experiments were carried out with the toxicants at dilutions ranging from 0.1 to 100ppm in which either 90% or 30% of the water containing larvae refreshed daily. Baytex produced 100% mortality for 3 to 4 days with 90% water refreshment and for 12 to 14 days at 30% water refreshment. DDT, dieldrin, and lindane produced almost 100% mortalities with 90% water refreshments for periods of 3 to 4 days, 3 to 4 days and 0 to 3 days, respectively. At 30% water refreshments, almost 100% mortalities were obtained for 4 to 14 days, 5 to 14 days, and 7 to 12 days, respectively, for these three toxicants. Under the conditions of 90% daily-water-refreshment, the residual effects of the larvicides DDT and dieldrin, which showed great reduction of the effect by adding the organic materials in the water of unrefreshed conditions, were decreased more rapidly by addition of the same materials into the water. On the other hand, Baytex, Sumithion, diazinon and lindane produced longer residual effects in water which included the materials thanin deionized water. DDVP was as effective in water including the materials as in deionized water. When excessive amounts of toxicant which produced complete death of the larvae were used, the granular form of Baytex was more effective than that of emulsion under the water refreshment. Factors influencing the residual effects of the larvicides, i. e., the aborption of the toxicants into organic materials, and the release of toxicants from the materials

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The biological and chemical analysis tests were conducted on adult houseflies to determine the residual effect of 0.3% DDVP oil solution fumigated in a room. The fumigation was done at the rate of 1ml per 1m^3 in the room where a veneer testing board was installed. The room was sealed for one hour after fumigation, and then the testing board was removed for testing. Houseflies of Takatsuki strain were continuously exposed to various surfaces of the board after two hours, three days, and six days of fumigation respectively and the time-knockdown data were observed. The residual deposit of the veneer testing board in two hours after fumigation was the most effective when it was placed at 5m distance from the jet nozzle and so the effect was most excellent when the surface faced vertically to the nozzle and in the descending order of the horizontal surface and parallel surface. The venner board in three days after fumigation showed an insecticidal effect on the surface facing vertically to the jet nozzle as well as on the horizontal surface at a distance of 5m. Even six days after fumigation, the insecticidal effect was confirmed on the surface facing vertically to the nozzle at 5m distance. Whereas the residual effect retained on the veneer board which was installed on the ceiling at 10m distance from the jet nozzle was noticeable for three days. However, the residual effect on the surface of a glass plate placed beside the veneer board was not recognizable. In case of substituting the testing board which was installed vertically to the jet nozzle at 10m distance for other ones, the insecticidal effect varies in the descending order of the painted veneer ≧ plain veneer > fiber board > textured board > polyvinyl chloride plate > mortared board. It is surmised from the above results that the fumigation of 0.3% DDVP oil solution gives to the indoor ceilings and walls the insecticidal deposit sufficient to kill houseflies.

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During July 12 to August 18, 1965, control tests of the diazinon resistant houseflies with Sumithion (fenitrothion) and a mixture of diazinon and isopropyl diazoxon were carried out in Mihara area of Hokota Village, Kashima-gun, Ibaraki Prefecture. While the laboratory test with the topical application method, the fly colony from this area proved to be more than 20 times as strong against diazinon as the normal colony. In three test areas, 0.5% diazinon emulsion, 0.5% Sumithion emulsion and 0.25% diazinon・0.25% isopropyl diazoxon emulsion were treated as residual sprays. In the case of Sumithion and a mixture of diazinon and isopropyl diazoxon, the fly population estimated by ribbon traps decreased considerably, but the effect of diazinon was always unsatisfactory.

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