In the case of inoculation, the polyhedra produced in the anterior part of midgut were larger than those in the posterior part, and those in the middle part were intermediate in size. The polyhedra appeared 48 hr after inoculation of the virus. At this time they were observed with difficulty in the cytoplasm around the cell nucleus of the midgut epithelium. The mean size of the polyhedra increased during the course of cytoplasmic-polyhedrosis. The growth rate of polyhedra was faster in the anterior part than in the posterior part, the middle part assuming the intermediate. On the variation of the size of polyhedra formed, the longer the time after the virus inoculation, the larger and more variable was the size of the polyhedra, and 120 hr after the inoculation the variability in the anterior part was larger than that in the posterior part. When the larvae were inoculated per os with larger polyhedra obtained from anterior part, and smaller ones obtained from posterior part, there was no difference in the size of the polyhedra formed between anterior and posterior parts, which indicated that the size of polyhedra is solely dependent on their position in the host midgut.

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In order to assess the parastic effeiciencies of two egg parasites, Asolcus mitsukurii ASHMEAD and Telenomus nakagawai WATANABE, which compete with each other for the egg of Nezara viridula, a large number of hosts were artificially placed in the fields and exposed to parasites for a short period, i.e. one week. The host finding ability of T. nakagawai was superior to that of A. mitsukurii and the period of residence on the egg mass was shorter in the former than in the latter. The percentage parasitism of egg masses invreased more rapidly in T. nakagawai than A. mitsukurii with an increase in their densities. T. nakagawai was able to parasitize the egg masses more efficiently than A. mitsukurii during the limited exposure of the egg mases. These facts show that T. nakagawai would be more promising egg parasite, if there were no competition with A. mitsukurii.

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A mass rearing method of the smaller tea tortrix, Adoxyophyes orana FISCHER VON ROSLERSTAMM, was devised by using paraffin papers as a barrier in a simplified artificial diet easily prepared with low-cost ingredients. It is not necessary to renew the diet during the period of one generation. The smaller tea tortrix has been successfully reaerd for 12 generations by this method, and about 5, 000 individuals are being reared in the laboratory.

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Implantation of a diapause brain into a diapusing Chilo larva did not cause the immediate termination of the larval diapause. But the same treatment terminated the diapause of decapitated larva. On the other hand, a diapause brain connected with the corpora cardiaca and corpora allata which was implanted into the decapitated diapausing larva produced little effect on the maintenance of diapause. These were quite different from the results shown in Ostrinia larva by CLOUTIER et. al. (1962). As a trial to approach the solution of the substantial relationship between the corpus allatum and the brain, some model experiments were conducted using physiologically active substances known to act like brain hormones in silkworms. Among the substances tested, cholesterol, diethylstilbestrol and noradrenaline induced the moulting of the headless, diapausing larva, though its percentage was low, wheras enone of them produced any physiological change in the intact diapausing one. Namely the activity of the chemicals was apparently inhibited in the intact diapausing larva. These results and others hitherto obtained seemed to give the evidence that the corpus allatum was responsible for maintenance of rice etsm borer larva in diapause.

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Infection of various tissues of Chilo suppressalis larvae with Chilo oiridescent virus (CIV) was examined by the appearance of iridescence. The CIV infected larvae were obtained by intrahemocoelic inoculation of CIV suspension under aseptic condition. The inoculated larvae ususally began to turn purplish 5 days after inoculation at 25°C. Pericardial cells and suboesophageal gland cells showed iridescence at first the iridescence was most prominent. The iridescence could be seen in these cells as early as 3 days following inoculation. Fat bodies showed the next prominent iridescence. Fat body lobules underneath the epidermis showed iridescence 3 days after inoculation, but large lobes distributed around alimentary canal showed iridescence much later and the iridescence was not prominent. Silk glands and salivary glands showed iridescence on some parts of the glands at 4 days following inoculation, but the iridescence appeared only on the surface of the gland. Hemocytes began to show iridescence 5 days after inoculation. In the larvae of advanced infection, hemolymph was turbid. Epidermal cells showed prominent iridescence 6 days after inoculation. Alimentary canals and Malpighian tubules began to show iridescence at 5 days following inoculation, but the iridescence seemed to appear only on the surface of them. In the prothoracic glands, iridescence appeared only in the posterior regious of the glands. At an advanced stage of infection, tracheal epithelium showed iridescence. Nervous system, gonads, and muscles did not show iridescence.

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From the studies made on the host and virus relationships among various strains of the silkworm, it has been demonstrated that the two cytoplasmic-polyhedrosis viruses, forming the tetragonal shaped and the hexagonal shaped polyhedra, are equal in virulence. On the other hand, the cytoplasmic-polyhedrosis virus seemed to be more infectious toward the silkworm than the nuclear-poly-hedrosis virus. General existence of a moderate but significant relationship between the interstrain susceptibilities to nuclear- and cytoplasmic-polyhedrosis viruses indicated that the mechanisms of the host to both the virus infections are similar to a greater extent.

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Effect of following insecticides on the isolated cockroach hindgut movement was investigated. They were organophosphorus compounds, carbamates, chlorinated hydrocarbons, nicotine, pyrethrins and several respiratory metabolic inhibitors. Nerve poison insecticides produced stimulatory action, and this stimulatory action may be mostrly related with cholinergic system on the hindgut. Lindane and some other chlorinated hydrocarbon insecticides, also classified as nerve poisons, showed weak stimulatory action and obvious gradual inhibition of the movement. Respirtory metabolic inhibitor insecticides produced gradual inhibition of the movement. High concentrations of insecticides blocked the movement, and recovery of the movement was obtained by repeated washing with new saline. Degree and velocity of the movement recovery depended upon the inhibitory nature of insecticides.

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