E. zinckenella is widely distributed in the southern half of Japan and seriously infests soy bean. However, this insect has not been investigated so far in Kantô district. This paper gives an account of field and laboratory observations on the bionomic and damage of the soybean caused by this pest at our experimental station.
The insect was found to undergo mostly three broods a year. The first brood moths emerged from the beginning of June and the peak of emergence was observed from late June through early July. The first brood larvae attack the pea or very early maturiting varieties of soy bean. The second brood moths appeared from the end of July through the first half of August and the larvae infested the early and medium varieties of the soy bean, but they were far less in abundance than the first and third broods. The third brood moths appeared from late August through mid-September and the larvae attacked the late varieties of soy bean.
The seasonal fluctuations in the number of eggs deposited and of the population of larvae in the soy bean fields were investigated at about 5 day intervals. The durations in which eggs were observed were well coincided with the duration of appearance of moths, and two large peaks were observed, one in July and another in September. The larvae were observed from late June with two population peaks, one in the latter half of July and another in the last 10 days of October and the first 10 days of November.
The scarcity of the second brood larvae seems to be attributed to the facts that the host plants which are at suitable stage for oviposition are very rare at the time of the emergence of the first brood moth and that the severe heat of midsummer in the latter half of July which causes a high percentage of mortalities of first brood larvae in the pods.
The damage of soy bean by the insect differed prominently among soy bean varieties owing to the maturing date of the varieties. The very early varieties were damaged seriously by the first brood larvae, and 30 to 50 per cent of the pods were infested. The early and medium varieties were hardly infested as the second brood is less abundant. However, the late and latest varieties were infested considerably by the third brood, 10 to 20 per cent of pod being infested.

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In the previous paper, the authors have reported that there were two geographical races in the rice stem maggot, Chlorops oryzae MATSUMURA. One of them distributes in the southern part of Japan and has three generations a year, whereas the other distributes in the northern part of Japan having only two generations. In the border region of the above two areas, populations consist of both races. Therefore, studies on the populations of such a intermingled region may contribute in increasing the knowledge of the geographical races in the rice stem maggot. From this viewpoint, the authors have conducted some ecological experiments on the maggot population of Kanose, the situation of which is in the intermingled region. The maggots from Kanose were transferred to Takada (threegeneration area) and were compared with those of Takada and Ômagari (two-generation area).
The results are as follows:
1. The emergence of the first generation populations of Kanose and Ômagari which were overwintered at Takada under natural condition occurred later as compared with that of Takada. Among these populations the emergence of Ômagari was the latest.
2. The authors have reported in the previous paper that the pupal duration of winter generation of Takada population was shorter than that of Ômagari. The pupal duration of Kanose population varied from short as Takada to long as Ômagari.
3. It was impossible to divide the Kanose population into two groups of two- and three-generation types with the emergence period of the first generation flies or with the variation of the pupal duration of winter generation.
4. The first generation larvae of Kanose were reared on young rice plants of susceptible variety. In this case, two kinds of larvae were observed; the one was quickly growing larvae which pupated soon after feeding only a few leaf blades remaining some arranged acars on the leaves injured at the later larval period, and the other was slowly growing larvae which did not remain arranged acars on the leaves and did not pupate before they fed young panicles. Besides these two kinds of larvae, somewhat slowly growing larvae which remained arranged acars and pupated before the heading of the host plant were seen.
5. Many of the quickly growing larvae seemed to come from the early emerged flies, while many of the larvae which came from the late emerged flies seemed to be the slowly growing larvae. The rate of slowly growing larvae in the first generation increased gradually with the delay of hatching period.
6. In respect of the quickly growing larvae, most of them pupated within thirty days regardless to hatching period.
7. In the next brood population which came from the cross of the Takada and Ômagari, most of the larvae became either quickly or slowly growing ones. This result was similar to the next brood population of the first generation flies of Kanose which had medium growing speed.
8. In F₃ population derived from the quickly growing individuals of F₁ which came from the cross of Takada and Ômagari, the quickly growing larvae appeared with high percentage. While, as to the F₂ population derived from the slowly growing individuals of F₁ the reverse result was obtained. The similar results were obtained as to the third brood population derived from the individuals of Kanose quickly growing in the first generation and the second brood derived from the individuals slowly growing in the first generation.
9. It may be concluded that the population of the rice stem maggot in so-called intermingled region represented by Kanose was the one derived from natural hybridization between the two races.

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It has been said that infestation of the rice plant by the rice stem borer, Chilo suppressalis, is severer in the Mizonobe-part of Kahoku-town, Yamagata Prefecture, as compared with that in the Kitayachi-part of the same town, 5km distant. Number of moths attracted by light traps was also more abundant in the former region than in the latter. For the differences observed in both regions, following reasons may be considered:
(1) The borers distributed in both regions are different to each other in their biological characters or injuring potencies.
(2) Some environmental conditions (including status of the rice plant) of Mizonobe-part differ from those of Kitayachi.
(3) (1) and (2) are taken place simultaneously.
From observations and experiments, it could not be concluded that the borers of Mizonobe are different from those of Kitayachi in their morphological and biological characters. Thus, reasons (1) and (3) are discarded out from the considerations.
Because of a short distance between Mizonobe-part and Kitayachi-part, it seemed that there is no difference in both regions concerning environmental conditions affecting borer's biology, e.g. climatic factors, natural enemies, planting practices, etc. Investigations showed, however, that physical and chemical properties of paddy soils of Mizonobe-part differ from those of Kitayachi soil. The greatest difference among them is the silicon supplying power of soils. Mizonobe soil contained a low level of available (easily soluble) silicon (8.9mg per 100g dry soil), while Kitayachi soil did a relatively high amount of available silicon (17.4mg per 100g soil).
Reflecting the silicon supplying power of soil, the rice plant grown on Mizonobe soil has a lower content of silicon as compared with the plant on Kitayachi soil. Silicon contents of the plant at harvest stage were less than 10% in Mizonobe and about 15% in Kitayachi. Consequently the former plant was seen to be more attractive to ovipositing adult moths, more preferable and less antibiotic to boring larvae, and less tolerant to borer infestation. It appears that silicon absorbed by rice plant gives to the host an allround ability on borer resistance. These interrelationships are illustrated as below:
As a result of supplying calcium silicate to paddy fields of both regions, rice plant infestation and borer population reduced remarkably in Mizonobe-part where soil was deficient in available silicon; whereas no influence was observed in Kitayachi-part.
Thus, the heavier infestation and higher population of the borer found in Mizonobe-part are explained clearly in a view point of low level of available silicon contents in soil of this region.
Some geological evidences on formation of Mizonobe soil were discussed in the text, with special reference to origin and translocation of granite sand as a parent material.

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Flower-visiting habits of 3 species of the genus Bombus were examined during from spring to autumn of 1951-1959. Nesting or flower-visiting activities were observed till early summer in B. ardens, and till autumn in B. ignitus and B. diversus, respectively. The number of flower-visiting workers became maximum during the periods of April-May in B. ardens, and June in B. diversus and B. ignitus.
The workers of B. diversus visited flowers of 76 species belonging to 31 families. Particularly, the flowers of Leguminosae, Labiatae and Liliaceae were visited predominantly by this workers. Moreover, they preferred mostly the flowers of Cirsium japonicum, Rosa multiflora, Vicia unijuga, Prunella vulgaris, Trifolium repens, Salvia chinensis, Impatiens textori, Pertya ovata, Astragalus sinicus and Styrax japonica.
The workers of B. ignitus visited flowers of 24 species belonging to 14 families. The flowers of Leguminosae were visited predominantly by them. These workers preferred mostly the flowers of Trifolium pratense and Vicia unijuga.
The workers of B. ardens visited flowers of 32 species of 18 families, especially, the flowers of Leguminosae, Rosaceae and Caprifoliaceae predominantly. And these workers rather preferred the flowers of Rosa multiflora, Rhododendron sp., Styrax japonica, Rubus parvifolius and Diospyros Kaki.

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The object of the work described in this paper was to investigate experimentally the overwintering of the brown planthopper eggs and the growth of the larvae hatched from hibernation eggs under the natural temperature condition.
Rearing of eggs were carried out in the weighing bottles containing the small quantity of water, absorbent cotton and filter paper under the natural temperature condition.
The larvae hatched from hibernation eggs were reared in the insectarium using the rice plants cultured in pot.
The results obtained are summarized as follows: 1) According to the results investigated by means of artificial rearing under the natural temperature, it was cleared that brown planthoppers hibernated easily in the egg form and the hibernation eggs hatched from the latter part of April to the early part of May.
2) As the results of successive rearing of the larvae hatched from hibernation eggs, it was cleared that the adults of the first generation emerged in the lastpart of May and the adults of the second generation in July.
3) In Kanagawa district, the first occurrence of the brown planthopper are found generally in the macropterous form (long-winged) at rice fields from the last part of June to July, and from the experiments mentioned above, it was considered that this adults were second generation.

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An attempt was made to gain some indications as to the role of X-ray and ultraviolet light in the induction of nuclear and cytoplasmic polyhedroses of the silkworm, Bombyx mori L.
No significant increase in spontaneous virus infection in the silkworm larvae resulted from exposure to ultraviolet radiation in the larvae exposed to the light alone and exposed to the light before or after cold treatment (5°C, 12-24hrs.). So it may be said that there was no indication that ultraviolet light induced the nuclear and cytoplasmic polyhedroses in the silkworm as reported in a few insects.
As shown in Table 1, there was no indication that exposure to X-rays enhanced the percentage of polyhedroses infected larvae, but in the case of the double treatments with X-rays and low temperature (5°C, 24hrs.), more virus-caused death resulted in the test larvae than in the control. The percentage of nuclear and cytoplasmic diseased larvae were markedly higher in those larvae treated with X-rays before and after cold treatments than in those treated with low temperature alone in the 5th instar larval stage soon after ecdysis.

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The author manufactured a homogenizes which can very easily have a uniform distribution of the diseased moth of silkworm, infected with pébrine. This machine is composed of a receptacle, so-called drum, which receives moths and of a water-tank which absorbs the scale of moths.
The former is the drum, which mixes moths. It is rotated by a stepped pulley, the velocity of which can be changed in three steps. In the drum, a agitation vane is inserted at 45 angle to the base. It serves to mix moths twice per rotation of the drum. Because, the vane brings the falling position of moths in the former half of one rotation to the fore part of the bottom of the drum and the latter half to its rear part or viceversa. Just behind the drum, this apparatus is provided with an electric fan, the rotation of which is about 4, 000r.p.m., in the metallic cover. The scale of moths is sucked by the suction power of the fan through the wire-netting, fixed to the hind cover of the drum, thus not only facilitating the microscopical inspection of ground moths by clearing the field but also by protecting healthy moths from contamination by the scale, heavily infected with pébrine. Moreover, absorption of the scale serves to keep the worker's sanitation, as the air of the room may not become dirty. The drum is made of acrylite (a name of stolen goods, made chemically of acrylic resin), so that the state of mixing manner of moths can easily be observed during rotation. Besides, in the case of the fore cover, as it is especially easy to fit it into the position or to remove it, so the manipulation of putting moths into the drum or taking them out from it is also done with no difficulty.
The latter is the water-tank, which receives the scale, blowed out through the wide suction pipe made of gum, which connects the former and the latter. It contains water and the large scale is absorbed in it. The upper part of the tank consists of the large tubular cover, whose side is covered by the bleached cotton-cloth and whose top is covered by the metallic plate. This cloth serves to catch fine scales and to pass out the air blowed in the tank. The surface of water is indicated by the level gauge.

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The effects of tea leaf powder, some fractions of tea leaf, fats and fatty acids on the larval growth and adult emergence of the smaller tea tortrix, Adoxophyes orana FISCHER VON RöSLERSTAMM, were studied with synthetic food media under aseptic conditions.
The optimum dietary level of tea leaf powder was evaluated as more than 22.4per cent of dry diet for both the larval growth and the adult emergence. The active principle for larval growth was partially extractable with boiling water, but not with ether; and that for adult emergence was pratially extractable with ether but not with boiling water.
So far as the activity for adult emergence is concerned, 1g of dietary tea leaf powder was replaced completely by either 50-200mg of linseed oil or 10-40mg of linolenic acid per flask. Olive oil, stearic, oleic, and linoleic acids had no activity. It was concluded that the smaller tea tortrix requires an unsaturated fatty acid, linolenic acid, in the food medium for the adult emergence.
Tea leaf contains some other unknown factor (s) essential for larval growth, which is partially soluble in boiling water.

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[in Japanese]

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