Experiments have been carried on to elucidate the relation of the population density of the false melon beetle, Atrachya menetriesi FALDERMANN, to the grass coverage and the legume-grass ratio in the grassland. Assessment of larval, pupal, and adult densities was made by direct count in the field. For the assessment of egg density soil samples were taken in early spring after the eggs became diapause-free and absorbed water from the soil. The egg were separated by a combined method of sieving and floatation. The results are summari-zed as folows:-
When 1 /600 a. sample unit was adopted in a mixed sward of the ladino clover and the orchard grass, number of individuals per unit area was apparently low, in every developmental stages, on units with very high coverage or with very low rate of legume. Using a sampling cylinder of 3.5 cm in diameter, it was confirmed that the eggs were deposited mainly on the parts covered with the ladino clover alone. In a field cage planted with the ladino clover, many of the released adults concentrated in oviposition period upon the plot with lower grass coverage. In conclusion it was pointed out that not only local distribution of the beetle but also the total population level in a grassland may be largely determined by the grass coverage and the legume-grass ratio through the process of habitat selection especially of the adult.

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Investigations were undertaken in order to ascertain the effect of mowing on the populatior density of the false melon beetle, Atrachya menetriesi FALDERMANN, in the grassland. The results are as follows:-
According to observations during several years at a ladino clover sward, the density of the beetle population including the egg stage was kept at higher level in the plot mown in the period of adult activity than in the check, except of an outbreak year in which case the density became lower in the mown plot than in the check because of emmigration of adults from the former due to the food shortage. Small scale field tests showed that in general the adult density was higher in the plots mown in the period of its activity than in the check during a few weeks just after mowing operation. As a result of the tests it was also found that in a mixed sward of the ladino clover and the orchard grass the number of eggs per unit area was much higher in the plots mown before and at the peak of adult activity than in the rest. In a field cage adults showed a marked preference to the part at which the grass was cut off just before releasing adults. Based on the results given above, as a means of preventing establishment of the beetle population at high level in the grassland, it was recommended to avoid harvesting during the earlier half of the period of adult activity. This means might be effective especially in large scale grasslands where the clover is mixed with gramineous plants not preferred by the beetle.

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Snice 1966 at a grassland in Kitakami mountain range, Iwate prefecture, the orchardgrasshas been severely damaged by the spotted spittle bug, Aphrophora stictica MATSUMURA. In 1969 and 1970, field experiments were undertaken to evaluate the effect of several insecticides for controlling the spittle bug. The results in 1969 were given in a previous paper (Kobayashi & Oku 1970). In 1970 the insecticidal application was made on May 18th just before the completion of hatching of the overwintering eggs, and the number of survivors was counted on June 5 th and June 26th. From the results in the two years, it was concluded that Bassa granules (5%), Bassa dust (2%), diazinon granules (3%), diazinon dust (2%), Baycid dust (2%) and Sumithion dust (2%) at 6K gper 10a, 0.1% solutions of Baycid emulsion (50%) and of Sumithion emulsion (50%), and 0.05% solution of Salithion emulsion (25%) at 130l per 10 a are substantially effective.

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This paper deals with Japanese weevils of the genus Hypera injuring leguminous pastures. In the course of the present investigation s the following five species have been known to occur in Japan.
1 Hypera nigrirostris (FABRICIUS)
2Hypera viciae (GYLLENHAL)
3 Hypera runzicis (LINN'E)
4Hypera basalis (Voss)
5 Hypera-adspersa (LINN'E)
1) Hypera nigrirostris (F.)
This species is the most important pest of pastures feeding principally on clover. In Japan its distributional range is restricted to the northern part of Honshu and Hokkaido.
The winter is passed in the adult stage. In the spring the beetles feed on the leaves of clover and alfalfa. The females lay their eggs in May, June and July. The larvae feed on new buds and axils of the host plants, and they pupate during June and July. The new adults emerge in late June to August. These beetles teke food actively for about two months, doing considerable damage to leguminous pastures. There is a single generation a year.
2) Hypera viciae (GYLLENHAL)
This species occurs only in certain zones on the coast of Hokkaido. It is less important than the preceding species. The adults feed on leaves and flowers of several kinds of vetches (Vicia sp.) in July and August. The adults often feed ravenously on the leaves of clover.
3) Hypera rumicis (L.)
This species has been known to be found on rhubarb (Rumexsp.) in fields of alfalfa in Hokkaido, but it has never been known to attack alfalfa.
4) Hypera basal is (Voss)
This species is widely distributed in Honshu, Shikoku and Kyushu but not in Hokkaido. The adult is found on chickweed (Malachium sp., Stellaria sp.) in fields of clover in Hcnshu, but it has never been known to attack clover.
5) Hypera adspersa (L.)
This species was once found on parsley (Oenathe sp.) in Gifu. The biology of this species has not yet been exactly known.
The adults of the Japanese species excluding H. adspersa are distinguished by the following key:
1) Scale strongly forked 2
-Scale slightly forked or not 3
2) Elytra with black markings on 1st to 3 rd intervals laterally. Honshu, Shikoku and Kyushu. Host plant: chickweed H. basalis
-Elytra clothed with green scales, without black markings. Hokkaido. Host plant: clover and alfalfa H. nigrirostris
3) Scale slightly forked. Hokkaido. Host plant: vetch H. viciae
-Scale not forked. Hokkaido. Host plant: rhubarb. H. rumicis

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The brown wheat mite (Homono-hadani in Japanese name), Peterobia latens (Müller), is one of major pests of crops in Hokkaido, devouring clover, alfalfa, wheat, barley, and many other grasses. Especially clover is severely infested.
This mite oviposits two types of eggs. One type, summer egg, is brick-red in color and possesses an inconspicuos central hair, and the duration of this egg is from five to ten days depending upon the climatic condition during summer and autumn. Other type, winter egg, is red in color and coated with a white substance. This egg began to hatch in late April orearly May in the next year.
Overwintering takes place only in egg stage. In the vicinity of Sapporo most of the winter eggs of this mite are laid by the female of second generation and the adult population reaches its peak on or about July 20th.

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The lesions of leaf blast caused by Pyricularia oryzae Cav. on leaves of rice plants wereinspected at the stage of primary infection in the paddy fields. All stands planted in 2.5-are field in 1961 to 1964, and plants grown in pots which were distributed at 24 spots in 4-hectare field in 1964 to 1967 and at 48 spots in 5-hectare field in 1968, and at 45 spots in another 50-hectare field in 1965 to 1968 were observed in Akita-ken.
When the lesions having grey centers with dark purple margins on the leaves of the same leaf-order appeared at first, it was designated as the initial stage of occurrence. Under the similar climatic conditions, inoculation tests were tried to evaluate the periods for developing such lesions. Based on the results, the date when infection occurred was estimated with twoday deviation.
After a period of more than 2 days at above 17°C, infection might be expected on a day without precipitation at night which followed to a period of more than 2 days with measurable rainfall. According to synoptic weather charts, there were low pressures in the eastward of the northern Japan and the south-westward of Kyushu, and the “Baiu front” moved to the southward by high pressure over Japan Sea.

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[in Japanese]

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1. Survey was done to know about disease severity of water melon inoculated with CGMMV-W at different growing stage of plant in field.
2. The latent period of this virus in the plant seemed to be about 15 days regardless. with growing stage.
3. The symptom on the leaves was mosaic with green mottle and it varried in severity as the plant grew.
4. The plant growth was poor with virus infection at any stage and damage was more. severe at the earlier infection.
5. The fruit was also affected when the plant was infected. The number of fruit decreased with earlier infection, and in case of the later infection many small fruit were set on the plants without any symptom.
6. If the plants were infected at the young fruiting stage, the fruit flesh became soften. However, the fruit of the plant infected at the other stages was fiberous. Even at the. later infection, the healthy marketable fruits were no more than 30% of the total yield of normal plants.
7. With these facts, it was indicated that the metabolism was disturbed in the diseased plant just after the infection, subsequently the fruits flesh became soft.

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[in Japanese]

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