A sexually mature female of the brown planthopper, N. lugens, vibrated her abdomen before the male approached her. This abdominal vibration seemed to be induced by the visual cue from the male. The visual cue was also probably important for the male to recognized the female. In some cases, however, the male failed to distinguish females from males of the same species or females of the small brown planthopper, Laodelphax striatellus FALLEN. When a male approached a copulated mature female, she showed a characteristic refusal response; an immature female did not show the response, but escaped the male's temptation. Males preferred brachypterous to macropterous females as their mates when both forms were under their choice. This may be ascribed to a behavioral difference between the two wing forms; the brachypterous female has a stronger tendency to stay on the plant than the macropterous female. The pre-mating period of females ranged from two to five days in the brachypterous form and from three to seven days in the macropterous. Many males became sexually mature within the first day after emergence and most by the second day. There was no apparent difference between the males of the different wing-forms in the frequency of copulation during the adult life. The male's ability to copulate increased for the first five days after emergence and then decreased.

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The radiosensitivity of the minute pine bark beetle Cryphalus fulvus NIIJIMA was studied for the radiation control of timber insects. The susceptibility to sterilization and inhibition of emergence by gamma irradiation increased in the order of eggs>larvae>pupae>adults.
The dose for sterilizing adults was about 15 krad at the most. The dose for inhibiting the emergence was 5 krad for 5-day old eggs, 7 krad for 3rd-instar larvae and more than 12 krad for pupae, and sterilizing doses for 3 rd-instar larvae and pupae were 6 krad and 8-9 krad, respectively.

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Various population densities of newly-hatched larvae of the cupreous chafer were reared in pots filled with mixture of fallen leaves and natural soil throughout nearly all the larval period and the larval numbers were counted at regular intervals. A remarkable effect of the initial density was observed in the larval survivorship. At lower initial densities, the survival rates of larvae decreased slowly with the time as a straight line in logarithmic scale and they kept still high levels at the end of the experiment. In higher densities, however, the rates decreased rapidly at the early period, and then slowly, reaching extremly low final levels.
Larval density seems to converge to a certain density level regardless of the initial density.
The fact might be due to the existence of limit of the larval survival for a given space.
Furthermore, when examing this converged level, there existed the optimum initial density producing the maximum final density. The high mortalities, occurring in early larval period, were highly density-dependent. This was probably not due to the low temperature in winter, the lack or excess of soil water content, any kind of predators, parasites nor the food shortage, but the fatal injury among the larvae encountered in the soil.

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Life tables for winter-spring generations of Pieris rapae crucivora, which had been accidentally introduced into the island of Okinawa in 1958, showed the basically similar mortality pattern with the spring populations of this species in the mainland of Japan. Due to the rareness of an important larval parasite, Apanteles glomeratus, and the lack of a pupal parasite, Pteromalus puparum, and the granulosis virus, total generation mortality was so low that the population density could rapidly built up through spring. Mark-recapture analysis of the adult population gave mean adult duration of 1.6 days for February and 2.9 days for March.

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In rice field of Saga prefecture, Kyushu, where BHC formulations had been applied frequently until 1969, the brown planthopper showed remarkable seasonal fluctuation of the susceptibility to lindane in 1969-1970. The autumnal generations were 14- to 19-fold resistant to lindane as compared with topical LD₅₀'s of those of the immigrant summer generation. The resistant laboratory strains originating from the autumnal generations were also resistant to dieldrin and fenitrothion, their resistance level being>19 times, and 6-7 times, respectively, when compared with the immigrant summer generation. While, there was no apparent difference in the susceptibility to carbaryl and DDT. No correlation was observed between the rate of absorption of the insecticides by the hoppers, as determined by gaschromatographic analysis, and the resistance to lindane and dieldrin. Environmental temperature, photoperiod (shorter days) and selection of brachypterous females had little effect in producing lindane resistant colony from the susceptible immigrant hopper in laboratory tests. These seasonal fluctuations were considered to be due to the alternate effects of the selective pressure of insecticides and replacement of the resistant population, which could not overwinter, with susceptible one which had migrated from distant areas not treated with insecticides.

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Investigations were performed at Naganuma in central Hokkaido from 1969 to 1972 to determine the distribution and food habit of the murid rodents in agrosystems by means of trappings (3 times/year) and stomach contents analysis. Among 4 genera and 8 species of the murid rodents known in Hokkaido, 6 species were trapped in cultivated fields and their environs during this research. Clethrionomys rufocanus bedfordiae was most numerous and was followed by Apodemus giliacus, Rattus norvegicus, Mus molossinus, A. argenteus and A. speciosus ainu. R. norvegicus and M. molossinus had similar food habits, however their habitats did not overlap, the former was abundant in paddy-fields and latter was in fields. A. giliacus, which was recently treated as an independent species, inhabited abundantly in woodlands in spring, then emigrated into cultivated fields in summer and autumn. It fed on as much animal materials as plant crops. It was showed that C. rufocanus bedfordiae, already known to be abundant in forest and grassland of Hokkaido where voles of genus Microtus were absent, distributed in this trapping area. But the proportion of the voles caught on the cultivated fields to the total catch of the species was low as compared with the above three species. A. speciosus ainu and A. argenteus were known as inhabitants of forest; they temporarily invaded cultivated fields.

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Investigations were performed on the diel activity of puncture to the host plant and active behavior such as wandering or take-off of the adults of the rhombic-marked leafhopper, Hishimonus sellatus UHLER. In the 2nd emergence period, the adults were moderately active for a time at the sunrise and active for a time before and after the sunset, but not active in other times. Their activity was apparently influenced by environmental conditions such as light intensity and temperature. They were active under 1, 000lux of light intensity, and light intensity adequate for take-off was about 1-200lux. Their basic periodicity was considered to be bimodal crepuscular type. But in the 3rd emergence period, unimodal crepuscular type, suppressed by low temperature was observed at the sunset or in the daytime. The threshold temperature for take-off was considered to be about 17°C. The number of punctures on the host plant was 117 for male and 81 for female in 48 hours, and was proportional to their active behavior such as wandering or take-off.

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