The Oriental fruit fly, Dacus dorsalis HENDEL, was successfully eradicated from the Amami Islands (1, 239km² in total area) by the male annihilation technique from 1968 to 1979. In 1968, aerial application of 97% methyl eugenol plus 3% BRP (naled) impregnated fibersquares was commenced to Kikai-Jima. The result was a marked fall of male flies caught by “monitor traps”. The number fell to zero after four months, and, although a few males were captured intermittently, the level was thereafter kept at a very low level. In 1974, the eradication program was extended to other islands including Amami-Oshima. The number of males captured and the percent of infested fruits at first fell drastically and thereafter maintained low level, but the eradication was not attained due to invasion from Okinawa-Honto, south of Amami Islands. Intensive control using large number of small squares or cut-ropes in place of small number of large squares and decrease in density of the fly in Okinawa-Honto by new control campaign resulted in eradication of this fly, from Kikai-Jima, Amami-Oshima and Tokunoshima at 1978 and from Okinoerabu-Jima and Yoron-Jima at 1979. Eradication was verified by examination of 118 traps for 190 days and of 309, 378 host fruits on Kikai-Jima, Amami-Oshima and Tokunoshima and by examination of 30 traps for 200 days and of 83, 222 host fruits on Okinoerabu-Jima and Yoron-Jima.

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In the course of behavioral studies on the courtship of Bombyx mori, tactile stimuli were found to play an important role in the final step of the mating process both in the male and female. The copulation attempt of the male was associated with the contact with the scales adhering to the female body. Especially, the scales which cover the last three segments of the abdomen of the female were important for the male to generate the copulation attempt. The male could most efficiently respond to these tactile signals when using their pro-thoracic legs as a tactile organ. On the other hand, both the contraction of the alluring gland and the lifting of the wings associated with the mating behavior of the female were induced by the tactile stimulus of the wings or abdomen of the male. Based on these results, the behavioral chain of courtship in B. mori has been proposed.

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The grape borer, Xylotrechus pyrrhoderus is a univoltine species, which hibernates at the larval stage. Effects of temperature and photoperiod on the development of this insect were investigated to analyse the environmental factors controlling the life cycle. Effect of photoperiod on the development of pupa, immature adult, and egg was not significant. Theoretical thresholds for the development of each stage were 10.5, 3.8, and 9.7°C, and thermal constants were 187.5, 224.0, and 114.1 day-degrees, respectively. The larval development was influenced both by the temperature and the photoperiod. At 20°C, few individuals pupated within the experimental period of 480 days, either under a long photoperiod of 16L:8D or a short photoperiod of 11L:13D. Several pupae were obtained under long photoperiod at 25°C. Higher percentage of pupation was observed only at temperatures of 27.5°C and 30°C and under long photoperiod. Under a short photoperiod, larval development was retarded, and the rate of pupation was low even when the temperature was as high as 30°C. The critical photoperiod for the induction of larval diapause (retardation of pupation) was about 13.5 hours at 27.5±3°C. The time of termination of the larval diapause was determined by transfering the overwintering larvae to a laboratory condition of 20°C and continuous darkness. Distribution patterns of pupation after transfer to the condition indicated that the diapause state was maintained until mid-November, and terminated between late November and December. Effect of photoperiod on the development of the hibernated larvae collected in April was observed but did not appear to be significant. It is suggested that the univoltine life cycle of this insect is maintained by the facultative diapause of larvae that require both long-day illumination and sufficiently high temperature for non-diapause development.

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The numbers of third-instar larvae of Neodiprion sertifer and colonies per red pine tree were counted over a 2, 400m² census area in Nagano Prefecture, in 1977. The area consisted of 303 red pine trees ranging from 0.5 to 6.0m in height. Total numbers of larvae and colonies were 16, 837 individuals and 496 colonies, respectively, and the mean number of larvae per colony was 33.95 individuals. The mean numbers of larvae and colonies per tree were 55.57 individuals and 1.64 colonies, respectively. The frequency distribution of the number of colonies per tree showed evidence of overdispersion, and corresponded to a negative binomial distribution with k=0.2843. The distribution pattern of the number of larvae per tree was aggregative, and characterized by the values of two parameters, α=39.04 and β=2.515 of the *m-m regression. The value of α indicated that the mean number of larvae per colony was about 40 larvae, and that of β showed the aggregated distribution pattern of the colonies. The mean colony size and the mean number of larvae per tree in the class of 2-2.9m height were the largest, and became smaller with the increase or decrease of the tree height. The density of the colonies was the highest at the northern edge of the census area, The mechanism of the distribution pattern of colonies is discussed in relation to the oviposition behaviour of the adult female.

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A milbemycins-organophosphate (OP)-resistant strain was obtained in the laboratory, against which the organophosphate insecticide isoxathion (ISX) and the brown oily mixture of milbemycins (BOM) were conspicuously ineffective. High synergistic effect of ISX and BOM on the adult mites, however, was observed when they were sprayed in mixture. Similar synergistic effect was also obtained with other OP-insecticides, especially O, O-diethylphosphorothioates and O-ethylphenylphosphonothioates in combination with BOM. Intoxication symptoms characteristic of milbemycins but not of OP-insecticides were observed following the treatment with the mixture. Recovery coefficient (LC₅₀ after 3 days/LC₅₀ after one day) of adult mites treated with the ISX-BOM mixture was lower than that with the BOM alone. When one of the preparations was sprayed for 2 consecutive days on the same mite population, spraying of ISX-BOM was more effective than that of the reciprocal BOM-ISX. From these results, it appears that the joint effect may be due to an inhibitory effect of the OP-insecticides on the detoxication process of BOM in the resistant mites.

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Populations of Therioaphis trifolii (MONELL) s. lat., which includes the spotted alfalfa and yellow clover aphids which are serious pests of alfalfa and clover were found on Medicago lupulina, M. denticulata and M. sativa (alfalfa) in Yamaguchi Pref., Japan in 1980 and 1981. Some specimens collected from Medicago sp. in Fukuoka City in 1944 also became available. Further surveys made near Fukuoka City in 1981 revealed the aphid on M. denticulata also. The Japanese specimens are briefly compared with the forms known from other parts of the world. The life history of the species in temperate Japan is not yet known. However, a life cycle in which the aphid reproduces parthenogenetically the year around as in warm climates is not likely. In temperate Japan, oviparous females and males may appear in the fall on unknown plant other than Medicago and give rise to overwintering eggs, or winged aphids may migrate every year from southern warmer areas. The distribution range, occurrence and likely future spread in Japan are also discussed.

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Mortalities of the green rice leafhopper ingested 2.8 and 5ppm cartap solutions were 50% and 80%, respectively. In rice plants roots of which were immersed in 40ppm cartap solution, cartap concentration in xylem rised to 5ppm after 10hr, and 95% of the green rice leafhopper released on the plants knocked down in 4hr. Electronic measurement of feeding activity showed that both 40ppm cartap in the root-immersion method and 5ppm in the parafilm method inhibited the feeding activity of the leafhopper owing to paralytic effect before they indicated apparent symptoms. Lower concentration of cartap (1ppm in parafilm method) also showed the inhibiting effect. The results well agree with the decrease of honey dew excretion and probing frequency by cartap. Furthermore, these explain the inhibiting effect of cartap on the transmission of rice dwarf virus by the leafhopper.

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Relationship between dietary conditions, and chemical properties of chorion of the silkworm, Bombyx mori, was investigated by means of electron probe X-ray microanalysis and differential thermal analysis. Sulfur, calcium, phosphorus and potassium were detected on the surface of the chorion by X-ray microanalysis. Among these, sulfur was the predominant component. It was demonstrated on the basis of spot-analysis, line-analysis, and surface-analysis that sulfur and calcium were distributed uniformly on the surface of the chorion. The amount of sulfur of the chorion was lower in the rearing on a semi-synthetic diet than in the rearing on a mulberry leaves. However, when the larvae were reared on a semi-synthetic diet supplemented with methionine and cystine, sulfur content of the chorion became as high as in the rearing on mulberry leaves. Results of differential thermal analysis of the chorion also supported the above results.

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Some of the life cycle parameters of the citrus red mite, Panonychus citri (MCGREGOR), were estimated by rearing experiments at constant temperatures of 12, 16, 20, 24, 28 and 32°C. The durations of egg stage and pre-adult stage, and the mean generation time (T) were 5.3, 9.1 and 11.7, respectively, at 32°C. At 12°C, these values increased by about 6-7 times those at 32°C. Developmental zeros of the egg and pre-adult stages were 7.4 and 8.2°C, and total effective heat was 123 and 217 day-degrees, respectively. All of these parameters such as total fecundity, net reproductive rate (R₀) and intrinsic rate of natural increase (r_m) were maximum at 24°C, and the values (in case of sex ratio 7_??_:3_??_) were 42.6, 28.3 and 0.171/day, respectively.

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Ten light traps were arranged in a line at regular intervals of 28.6m between two forests about 200m apart from each other. Comparison between the catches of moths by these traps was made. The catches were the greatest both in relation to the number of individuals and to the number of species within about 30m from the forest edge. It was considered that these peaks of the catches near or at the forest edge resulted from the flights of woody plant feeders from the forests. On the other hand, herb and grass feeders were collected almost uniformly among the traps in the field lying between the two forests. The traps at both extremities were set in the forest and the catches of these two traps were remarkably fewer than those of the other 8 traps. There were no species collected exclusively in the traps in the forests. From the above, it was considered that, for the study of moth community, a range of about 30m from the forest edge is the most suitable for the setting of light trap.

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Various group sizes of hatched larvae were allowed to attack rice at different stages of growth. When rice reached the later stages of growth, the percentage of survival of larvae after 1-day hatching increased gradually with the group size whereas in the case of rice in the early stages of growth no correlation between survival and group size was recognized. Survival rates of larvae differed according to the growth stage of rice: the survival rate of the smaller group size decreased with rice development, though that of the larger group size increased until the booting stage. Mortality of boring larvae up to 5 days after hatching was generally low irrespective of the group size of the larvae and the growth stage of rice.

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The difference in the susceptibility to nuclear-polyhedrosis virus between diapausing and non-diapausing embryos, was studied using eggs from the Daizo and E 16 silkworm strains having a different degree of susceptibility to the virus infection. The naked eggs were cultured by the hanging-drop method and incubated for a prescribed period of time after adding the virus in a known concentration into the culture medium. The results indicated that the diapausing embryo was considerably less susceptible to the virus infection than the non-diapausing one. The difference in the susceptibility was larger than that between silkworm strains. The addition of ecdysterone into the culture medium increased the susceptibility of the cultured diapausing embryo to the virus infection. On the other hand, the culture medium containing extract from the body fluid of the molting silkworm affected the growth of the cultured embryo and caused a lower ratio of virus infection than that containing the body fluid of feeding silkworm.

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Liquid insecticide containing 20% isoxathion which was spread over the paddy water showed high toxicity to the rice plant weevil for three days after application. This insecticide was thus applied to the paddy water for various periods of time (0∼6 times) at three-day intervals during the period of migration of the rice plant weevil into the paddy field, and the percentage of injured leaves caused by the insect was compared among the treatments. The results indicated that the application of this insecticide twice suppressed effectively the occurrence of injured leaves. The lethal period in the plot where the application had been carried out twice was estimated to be about seven days after the treatment based on the relation between the amount of isoxathion in water and insect mortality. These results suggest that the period for controlling the rice plant weevil to keep a low injury level was only one week although this insect invades the paddy field for more than one month. This period coincided with the time when the population density of the insect in the paddy field reached about 60% of the peak.

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The incidence of Platypleura kuroiwae MATSUMURA, which originally inhabited the forests and bushes of the northern Ryukyus, has increased in the sugarcane fields of some areas of the main island of Okinawa and Okinoerabu-island since 1973. The density of nymphs per sugarcane stool sometimes exceeded 100 resulting in the decrease of the number of newly sprouted stalks. Adults laid eggs only on dead sugarcane leaves, and when many dead leaves remained in the sugarcane field the insect was able to repeat generations within the field. It is suggested that the density of the cicada could be reduced below the economic injury level by removing dead leaves along with regular ploughing of the sugarcane fields.

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