At an early stage of development in Heterodera glycines ICHINOHE, irregular bodies were observed in cysts. Phenolic substances were detected at higher concentrations in brown cyst walls than in those with a pale-yellow coloration. These substances were primarily detected in the outer half of the brown cyst wall. Under the electron microscope, the layers of the cyst wall were more clearly observed in brown cysts than those exhibiting a pale color, because of pronounced differences in electron density among layers which were progressively being taned. A fibrous layer with high electron density developed in the innermost layer (C₃) subsequent to the yellow-brown cyst stage.

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The spatial distribution of 11 oribatid species obtained from forest and grassland was analyzed using IWAO's ρ-index. Ten species were distributed contagiously. Colonies were loosely distributed in forest plots, but many were compact and small in grassland plots. Two species, Oppia nova and Tectocepheus velatus were found in all eight plots examined, and their degree of aggregation was higher in forest than in grassland plots. In the Picea-moss forest, degree of aggregation was lower in early winter than in spring, despite an increase in population density in early winter.

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The male of Papilio xuthus, a Japanese black-and-yellow Swallowtail butterfly visually determines his conspecific mate during courtship. Field experiments with various dummies and models reveated that the visual releaser of the male's approach is not the color of the wing alone but its striped pattern of black and yellow.

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Drosophila flies were released into dikes surrounding a paddy field during the period from late April to mid-July as an alternative prey of spiders. Flies were found to be devoured frequently by spiders and constituted 39% of the spider diet. The population density of spiders in the dikes increased soon after release and was followed by an increase in paddy fields situated adjacent to the dikes. The population density of leaf- and planthoppers inhabiting these plots was suppressed during late July in the dikes and during early September in the paddy fields, but the suppression was not evident thereafter. These results suggest that the abundance of spiders in any given paddy field depends upon the extent of food availability prior to migration from dikes, and that their predatory pressure upon hoppers is not significant.

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The resumption of motility of the motionless 4th-stage larvae of Paratylenchus aciculus, collected after storing in host-free soil for 60 days, was induced by immersion for about 7 hr in either distilled water or root exudate of host plants. However, the root exudate induced the 4th-stage larvae to become lethargic prior to the final molt more rapidly than did distilled water so that there was a higher rate of adult emergence in root exudate than in distilled water. The log activity value of the mulberry root exudate used was 4.04. The time necessary for receipt of the stimulating substance was at least 24 hr. Lethargic larvae in the final molt were no longer able to survive under adverse conditions. The ecological role of the 4th-stage larva in the survival of this species is discussed.

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The host plant specificity of the cucumber looper, Anadevidia pepnis (FABRICIUS), which is harmful to most cucurbitaceous plants, was analyzed experimentally by examining its responses to 27 species of the host and non-host plants in six steps in its host selection, i.e., oviposition of the adult, orientation, biting, feeding and staying of the newly-hatched larva, and nutritional suitability of the plants for its development. The cucurbitaceous host plants were all acceptable with the factors in these steps. Gynostemma, a cucurbitaceous non-host plant, was found to have a powerful feeding deterrent(s) and no oviposition-promotive factor. Non-cucurbitaceous paulownia, which is occasionally attacked by the insect, was an exception in eliciting all positive responses.Oviposition was promoted also by moisture even if the characteristic factors of host plant were completely absent. Some non-host plants represented by cabbage, elicited its positive reactions in every step but in oviposition. The fact that a few larvae of A. peponis have occasionally been found on cabbage farm suggests that cabbage becomes a temporary host when the larvae contact with the plant in some way. Many other test plants appeared not to become the hosts because they possess one or more negative factors against the host selection of the insect.

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The effects of gamma radiation applie to melon fly pupae 2 days before adult emergence on the rate of eclosion, adult longevity and fertility were evaluated. A dose of 6000 R gave complete sterility of the females, but this dose sometimes gave a low fertility of males. A dose of 8000 R gave complete sterility of males. There were no significant differences in the rate of emergence and adult longevity between untreated flies and flies treated with 6000 R or 8000 R.

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Since the attactive plant-phenolic compounds were postulated to occur in the mosquito-breeding field waters, the attractancy of woodcreosote for mosquito oviposition was investigated with 5 species mosquitoes in 6 colonies.The chemical analysis of creosote with a GC-Mass spectrograph revealed 20 homologus and analogus phenolic constituents.Eleven chromatographic fractions and 11 authentic compounds were bioassayed. Both 3, 5-xylenol and 2, 3-xylenol were quite attractive to the Denken colony of C. p. pallens individually and in the mixed fraction, but to Ar. subalbatus only the mixed fraction was so. 3, 5-Xylenol and its mixture with 2, 3-xylenol was also attractive to A. togoi. 2, 3-Xylenol and its mixture with 3, 5-xylenol was attractive to A. aegypti. 2, 6-Xylenol was also attractive to A.aegypti.The creosote included other compounds such as 2-methoxy-x-methylphenol attractive to the Denken colony of C. p. pallens, trimethylphenols attractive to C. p. molesuts, and 2-methoxy-x-methylphenol attractive to C. p. pallens, C. p. molestus and A. togoi. The alkyl moiety of these attractive compounds are presumably on 3- or 6-position of the benzene ring judging from the configurations of the above attractive dimethylphenols.Since the attractancy of natural material such as the creosote is derived either from single attractive constituent or oftener from combination of the attractive and closely related inactive compounds, the complete chemical analysis and the bioassay on every combinations of the related constituents are suggested to obtain the best formula for oviposition attraction.

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