The emergence and spread of the injury to rice plants by Chilo suppressalis in its first generation were studied in Takada, Niigata Prefecture, in 1965 and 1966. In the former year, the injury which was regarded as being caused by borers originated from a single egg mass was analysed. The injury did not spread concentrically from the hill of rice plants on which the larvae had hatched. More complicated methods of analysis were necessary for the data obtained in 1966 than for those in the preceding year, because clusters of injured plants of different origins existed often overlapping one another. MORISHITA'S C_δ-index was available for indicating the intensity of the overlapping of clusters between two research dates. The tendency was detected that the extent of convergence was lower in the distribution of clusters which appeared on June 10th or so than in the distribution of those which appeared near the end of that month.

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The cabbage stink bug was classified as Pentatomorpha in respect to the external structure of its salivary gland. The form of the posterior lobe, especially the width of its basal portion, varied slightly within the individual species of Pentatomidae. As regards the external and histological structure of the salivary gland of the bug, no essential difference could be discerned among the different stages except for some minor features. It was supposed that the function of the anterior lobe differed from that of the posterior. This could be inferred from the apparent difference between them with regards to the distribution pattern of the contens of the sack and from the existene of large granular substances in the cytoplasm of secretory cells in the anterior lobe. The cytoplasm in both of the lobes cotained vacuoles which varied in number and location with the individual bug of the same species. This suggested that the secretory cell had a continuously varying secretory stage.

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Localization of the structural precursors of sheath material in the salivary glands of Nephotettix cincticeps UHLER and Laodelphax striatellus FALLEN was investigated. In N. cincticeps, the sheath material originates as two distinct secretions, protein and probable mucolipid, produced respectively in the IV- and V- cells in the principal gland. In L. striatellus, the precursors, protein and unsaturated lipid, elaborated in the A- and coupled G- and H-follicles of the principal gland respectively. In addition, a certain mucosubstance in the accessory gland may enter into the sheath material.

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Gregariousness has been found in the german cockroach, Blattella germanica L. Young nymphs of the german cockroach aggregate when they are resting. When newly hatched nymphs reared in solitary, the growth and development were delayed. The gregariousness is considered to be favourable for the existence of this insect. The facts that the aggregation was observed even in darkness and that the antennae played an important role for the aggregation suggest that chemical stimuli would be responsible. Active principle responsible for the aggregation was found both in the faeces and in ether washing of the body surface. Ether washing of the posterior portion of the abdomen showed higher activity than the other portions. These results indicate that the active principle would be produced either externaly or internaly in the region of the anus. As the result of histological studies, it was found that the epithelium of the rectum forms six rectal pads consisting of single layer of cells showing glandular nature. Filter papers conditioned with the german cokroaches whose abdominal tips had been amputated did not elicit the response for the aggregation, while those impregnated with methanol extract of the rectums dissected did. It is concluded that the active principle seems to be secreted from the rectal pad cells into the lumen of the rectum when faecal materials are passing, and then excreted with the faeces. The active principle found in the body surface was considered to be of the same origin as found in the faeces, and it adsorbed onto the body surface by its lipid nature. This active principle playing as an attractant for the aggregation seems to be a new kind of pheromone. We offer the term "aggregation pheromone" to this pheromone.

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Craetopycrus cornutus and its associated species of mite of the genus Pygmephorus were recorded for the first time in Irap. The characters of various stages of the beetle were noted, measurements on these were done and certain aspects of life cycle were worked out. Incidence of the parasitic mite on the beetle host during 1966-67 was observed and the host-parasite relation and pathology were discussed. A series of measurements on the nymphal and adult stages well carried out and on the basis of laboratory and field observations the life cycle of the mite was suggested.

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