Mass rearing and single female rearing of two species of Hirschmanniella were conducted. Adults of H. imamuri penetrated and moved into the roots of rice seedlings in a seed bed and laid their eggs during a comparatively short time. Hatched larvae lived within root cortical layers for some time, and then the matured larvae left the roots and into the soil to become adults. However, attempts to learn the mode of life of H. oryzae was found to be difficult because the morphologycal differences among the larval developmental stages were insufficient for identification of each stage. As results of this study it is considered that one genaration a yeare is commen with H. imamuri, but two generations a year for H. oryzae.

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The author studied the life history and the percentage parasitism of Dolichomitus sp., a parasite of the pine bark weevils, by field observations, and also the development of one generation through laboratory observations. Oviposition was mostly observed on pupae and prepupae of Shirahoshizo spp. and Niphades variegatus ROELOFS from the beginning of July to the end of September. The emergence of the parasite was noted from the end of July to the middle of October. Some larvae overwintered and the adults emerged at the beginning of April. The percentage parasitism to the first generation of Shirahoshizo spp. was 15.8% and that to the second was 27.4%. Egg stage was 2-6 (male) and 2-3 (female) days, the first instar larva-1 (m. and f.), the second-1-3 (m.) and 1-2 (f.), the third-1-2 (m. and f.), the fourth-1-3 (m.) and 1-2 (f.), the fifth-2-7 (m.) and 1-2 (f.), the sixth-3-6 (f. only), pupal stage-2-5 (m.) and 3-5 (f.), and the period from an egg to an adult under laboratory conditions (20-32°C) was 14-21 (m.) and 15-21 (f.) days.

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The influence of fertilizers on host plants and the occurrence of the root-knot nematode, and on the efficacy of nematicide were investigated. Tomato (cucumber in the next year), red clover and sweet-potato plants were cultured with compound fertilizers alone (400g/3.3m²), with compost manure alone (30kg/3.3m²), and without fertilizers for 2 years. Nematode population density in soil, fecundity of adult females, and emergence of adult males and brown egg masses were estimated. Nematicide EDB was applied at the time of harvesting or in the next spring to each plant. After the nematicide application, sweet-potato plants were cultured in all plots with habitual fertilization (chemical compound fertilizers 100g/3.3m², compost manure 10kg/3.3m²). The results were as follows: (1) The increases in small male adults with one testis and in brown egg masses were accompanied with the rapid maturity of the nematode on plants without fertilizers. The larval density in the soil was maximum in the early growing stages of these plants. (2) The peak of larval density occurred in the latter half of plant growth receiving chemical fetilizers alone. Large males with two testes were increased. Continuous application of chemical fertilizers caused an increase of the nematode population. (3) Larval density in the plot with compost manure reached its maximum at the harvest time of the plants. (4) In the plot with compost manure, application of EDB in autumn (harvest time) was more effective than in the next spring. On the contrary, spring application in the plots with chemical fertilizers alone or without fertilizers was rather effective than previous autumn applications.

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The honeydew excreted by the brown planthopper, Nilaparvata lugens (Stål), was studied quantitatively and qualitatively with special reference to the planthopper feeding. The frequency of excretion in the female adults varied from 7 to 40 droplets per hour, and the average droplet volume was 0.06 to 0.09μl in most cases. The rate of excretion was therefore estimated at 0.5 to 5μl per hour during feeding. The total amount of daily excretion in one female was 13μl on an average. Although the average concentration of sugars, mainly glucose and sucrose, was about 2%, the planthoppers excreted considerable amount of sugar-free excreta as well as sugar-containing ones. This two fold nature of the excreta might suggest that the insects ingested both the phloem and xylem sap of rice plans. About 0.1% amino compounds occurred also in the honeydew. The main amino acids and amides were glutamic acid, glutamine, aspartic acid, asparagine, and arginine. One female adult was estimated to discharge about 12γ amino compounds and 266γ of sugars every day through excretion.

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The testicular development and changes of cellular components in the testes of Hyphantria cunea were studied at various stages from the 3rd instar larva to adult. The paired testes of the larva were located dorsally in the 8th segment, but became fused into one at the time of pupation. The testes of the 3rd instar larva were light yellow in color and as the insect aged, large amounts of pigment were deposited in the capsula lobli (an inner testicular membrane) and the testes became brownish black. The testes of the 3rd and 4th instar larva contained essentially proliferating spermatogonia and premeiotic spermatocyte cells. Considerable meiotic activity took place during the 5th instar. Spermatids and eupyrene sperm bundles were first observed in the 6th instar. In the 7th instar, the testes were filled with mature eupyrene sperm bundles and little meiotic activity was present. The testicular elements in the pupal stage consisted primarily of mature eupyrene sperm bundles, and those of apyrene were very few in number. Furthermore, no pronounced difference was observed in spermatogenesis between diapause and non-diapause pupae.

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