From April to July of 1956, the field population count of the common cabbage butterfly was carried out to study the factors affecting the natural mortality on a cabbage field of National Institute of Agricultural Sciences. In the present paper the authors described the results of this study and concurrently attempted a comparison with the results of the preceding observations already reported (MIYASHITA, ITÔ & GOTOH, 1956).
The cabbage field of 1 acre in area was covered by a 8-mesh net to keep the butterflies off. This field was also divided by the net into two sections both of which contained 128 cabbage plants.
Ninety-four second brood butterflies (44 males and 50 females) collected in the suburb of Tokyo were released into section B of the experimental field on April 21, and were eliminated after two days.
Counts of numbers of eggs, larvae, pupae, and individuals succumbed to parasite and disease were conducted on all plants until the whole insects pupated. All the pupae were removed from the field and kept in the laboratory. When the third brood butterflies had emerged from these pupae, each one-thirds of butterflies emerging every day were released on the same day into section A of the field, and were allowed to oviposit until their deaths. Fourty pairs of the third brood butterflies were also liberated into section B on June 8 and eliminated on June 10. Counts were made in both sections, as in the 2nd brood.
The results of these counts are shown in Tables 1, 2 and 3, and the survivorship curves calculated from these tables in Fig. 1.
In every case, remarkable reductions in the number of individuals were found at three developmental stages, i.e. the egg and the first larval instar, the last larval instar, and the pupal stage. The second, third and fourth larval instars showed no conspicuous decrease.
From the comparison of six different generations reported here and in the previous paper, the following conclusions could be drawn.
1. Except the mid-summer generation of 1954, mortalities of the egg and the first larval instar were estimated as 50 to 70 per cent of the initial number of eggs. These mortalities seemed to be caused by the mechanical effect of weather and by the predation of polyphagous predators. In mid-summer generation of 1954, predation of eggs by Orius bugs played a dominant rôle in an extraordinary high mortality.
2. Mortalities of the last larval instar varied in different seasons and were always attributable to the “wilt” disease and to the parasitism by Apanteles glomeratus. The rôles of these factors seemed to be intensified by genaration by generation except that the parasitism decreased temporarily in the mid-summer generation. The increase rates from the preceding generation were larger in the second and the third generations of 1956 than in the third generation of 1955. In 1956, this high increase mainly due to the less propagation of the parasite.
3. Mortality at the pupal stage was due chiefly to a pupal parasite, Pteromalus puparum. Parasitism of this species was higher in the third than in the second brood.
In conclusion, abundance of the common cabbage butterflies seemed to be controlled by the mechanical effect of weather and the activity of predators, two species of parasites and “wilt” disease. The weather and the predator affect the early developmental stages, while parasites and the disease affect the last larval and pupal stages. Temporary decrease of the population in the mid-summer generation may be attributable to the density-dependent increase in the activities of biotic factors and the harmful physiological effect of high temperatures. As for the activity of predation against the fullgrown larvae and the overwintering pupae, future studies are needed.

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Lagynotomus and Aelia which belong to the Family Pentatomidae (s. str.) are represented in Japan each by one species, Lagynotomus elongatus (DALLAS) and Aelia fieberi SCOTT. The former species is one of the most important pests of the rice and other cereal plants. The latter is also known to attack sometimes these plants. Lagynotomus is closely related to Aenarai which is represented in Japan by only one species, Aenaria lewisi (SCOTT), the larval stages of which were already reported by the author in 1958. The developmental stages of the two species, Lagynotomus elongatus (DALLAS) and Aelia fieberi SCOTT, together with their ecological notes, are given in this paper.
The diagnoses of the Genus Lagynotomus
Egg: Short-elliptical, slightly depressed, pale yellow or yellowish white at first. Chorion pale white, subhyaline, surface with microscopically granulous structures which are connected by irregular lines. Micropylar projections nearly subhyaline, rather short-capitate. Egg-burster blackish brown, well-chitinized, T-shaped, with membraneous appendages which are mostly dark except the transparent centre. Operculum distinct. Eggmass ordinarily consisting of about 10∼16 eggs, arranged in one or two, rarely three rows.
Larvae: Stigmata placed interior to connexiva of abdominal segments from second to eighth, the eighth pair conspicuously smaller than the others. Body nearly short-ovoid in the 1st instar, ovoid in the 2nd, elongate-ovoid in the 3rd, fusiform in the 4th and 5th instars. Head short, arched in the 1st instar, rather long in the 2nd to 5th instars; median lobe considerably wide and longer than lateral lobes in the 1st and 2nd instars, comparatively wide and almost as long as lateral lobes in the 3rd, rather narrow and more or less shorter than lateral lobes in the 4th, considerably narrow and shorter than lateral lobes in the 5th instar; lateral lobes not angular apically, more or less produced laterally in front of eyes in the 2nd to 5th instars. Abdominal dorsal plates absent in the first and second segments; the plate of the anterior odoriferous gland orifices wider than the other of the median orifices, fusiform, and conspicuously constricted medially in the 1st instar, while the former is rather narrower than the latter, fusiform, and considerably constricted centrally in the 2nd to 5th instars. Lateral margins of thorax serrated, clearly in the 2nd to 4th instars, slightly in the 5th instar. Body sparsely with short hairs. Head and thorax very sparsely with black punctures in the 1st instar, rather sparsely with fuliginous or black punctures in the 2nd and rather densely with black or fuliginous punctures and reddish dots in the 3rd to 5th instars except the lateral parts of thorax in the 4th and 5th instars. Abdomen through all instars samely punctate as thorax and in the 2nd to 5th instars scattered with reddish dots. Body without conspicuously coloured markings.
The diagnoses of the Genus Aelia
Egg: Elliptical, somewhat wider towards above, very light brown at first. Chorion extremely light brown, with a brownish reticulation which is furnished with light brown or darkish small spines. Micropylar projections white except the bases which are nearly subhyaline, rather short-capitate. Egg-burster well-chitinized, T-shaped, mostly black except the brownish superior portion of axis, with membraneous appendages which are mostly transparent except the dark inferior ends. Egg-mass ordinarily consisting of about 12 eggs, arranged in two rows.
Larvae: Stigmata placed interior to connexiva of abdominal segment from second to seventh. Bodies rather long-elliptical in the 1st to 3rd instars, rather fusiform in the 4th and 5th instars, and with a luster and short hairs sparsely through all instars. Head wide, lunate in the 1st and 2nd instars, semicircular in the 3rd instar, rather conical in the 4th and 5th instars

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The larval growth of the rice stem maggot of the second brood was studied on rice plants sown at different dates and at various stages. On young plant of susceptible variety, Shirogane, most of the individuals grew to the second and third instars in ten to fourteen days after hatching except some individuals remaining as the first instar. The larval growth was excellent on the host plant at the formative stage of young panicle. On the plant in the stage between the above two, the growth of the hatched larvae was retarded and almost all the individuals remained as the first instar even on the eleventh or fifteenth day after hatching. This retardation of growth was observed from 10-leaf stage or from the latter parts of the vegetative growth, although there were small differences between the results obtained in 1958 and 1959.
This relation of larval growth to the host condition effected the occurrence of the rice stem maggot. In the districts where three generations occurred, the duration from oviposition to emergence of fly was longer in the second generation than in the first generation. In the districts of two generations, the larval growth was retarding until the host rice plant began to form the young panicles. The growth of the hatched larvae was suppressed as the hatching of larvae coincided with the latter part of vegetative growth to formative stage of young panicle. The said principle is also related to that the late varieties develop rather few injured panicles although they are originally susceptible, and that the early varieties develop injured panicles more although they are originally less susceptible.
In a Spanish variety, Bombar, no remarkable relationship was found between the larval growth and the stage of host plant and the larvae grew very rapidly. This variety seems very susceptible to the rice stem maggot. Accordingly, there may be some differences in the details of the relationship between the host plant stage and larval growth, although the general pattern of the relationship is the same.

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Previously the author discussed the effects of various temperatures on the developmental velocities of each stage of the Asiatic common looper, Plusia nigrisigna WALKER. In the present paper, the author wishes to deal with the effects of temperature on the body weight of the pupae and on the mortality during the larval and pupal stages of this species. Observations were also made on the colouration of the larvae and pupae. The materials and the method of experiments are described in the previous paper. Two constant temperatures of 25°C and 30°C, and various room temperatures were used, and the larvae were bred under crowded (20 individuals per container) or solitary condition.
1. The body weight of the pupae (4∼24 hours after pupation) was little different between two cultures fed on the cabbage, Brassica oleracea, and on the rape, B. campestris, respectively. No significant sexual difference was observed between them (Table 1).
2. The body weight of the pupae was not significantly influenced by the temperatures tested, but under high temperature of 30°C a few extremely small pupae were obtained (Table 1).
3. The mean body weight of the pupae in the solitary culture was slightly greater than that in the crowded culture, but the difference was not significant (Table 2).
4. The mortalities of the larvae and pupae rose abruptly when reared at 30°C, death mainly occurring in the pupal period (Table 3).
5. In the genus Plusia, the pattern of appearance of black spots or black colouration on the head, legs, pinacula or skin points of the larvae seems not to be constant within a species, and wide-range intraspecific variations exist depending on the degree of cuticular melanization. In P. nigrisigna, it seems that neither temperature nor population density can be regarded as the main factor responsible for the variation of the colouration.
6. The pupae showed marked differences in colouration depending on the degree of cuticular melanization. This degree of melanization was shown to be directly dependent upon temperature during the larval period. The pupae were yellowish brown when reared at 30°C during their larval period, deep black at about 20°C or lower, and intermediate in colour at 25°C (Table 4 and Plate 1).

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1. Interrelation between warfarin concentration, bait consumption per day and mortality: With successive administration of poisoned bait containing more than the minimum effective concentration of warfarin, it was found that the time or amount of bait consumption per day and the numbers of times of administration are more responsible for mortality rather than the concentration of warfarin.
2. Interrelation between warfarin concentration, time of bait consumption, prolongation of prothrombin time and mortality: The greater the consumption of warfarin bait per day, the lower was the concentration needed for the distinguished prolongation of the prothrombin time of the poisoned mice and for the high mortality. However, there was no close relation between the days of survival, warfarin concentration and the days necessary for the prothrombin time to attain over 300sec.
3. The resistance of blood capillary decreased markedly in parallel with the increase in prothrombin time and in the numbers and times of administration, but no obvious relation was found between the resistance of blood capillary and warfarin concentration.
4. Haemorrhage in the mice killed by warfarin could be classified into nine types based on the degree of haemorrhage. Among these, the haemorrhage types of the brain and the digestive organ were predominated.
5. From the results of studies up to date, it is concluded that the decrease of blood capillary resistance running parallel with the prolongation of the prothrombin time plays a major role in the toxic effect of warfarin.

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The insertion of stylets into host plants has been studied in 34 species of aphids belonging 25 genera. Aphids feeding on host plants were quickly paralyzed with ethyl ether, and plant portions with aphids were fixed by formalin (10%) for 24-48 hours. Paraffin sections, 15μ thick, were stained with DELAFIELD'S hematoxyline, safranine T and acid fuchsin. The main results are summarized as follows:
1. In most species the stylets are inserted into epidermis intercellularly, intracellularly or sometimes through stomata, but Ceratovacuna lanigera ZEHNTNER on Miscanthus and Schizolachnus orientalis TAKAHASHI on pine leaves insert the stylets into the plants always only through the stomata of the leaves.
2. In many species the stylets inserted in plant tissues pass usually intercellularly, and also frequently intracellularly through even cells containing crystals, but insert intercellularly in sclerenchyma or parenchyma. Schizolachnus orientalis TAKAHASHI inserts the stylets always intracellularly through the insert parenchyma and endodermis of the leaves of Pinus densiflora.
3. The stylet sheaths or salivary sheaths are usually more developed within cells than between them and are formed even in air between the tip of rostrum and the surface of plant epidermis, or between the leaf sheath and the stem, when aphids feed on the stem through the sheath.
4. The stylets usually reach phloem, especially sieve tubes, but were observed reaching xylem or bundle sheaths in a few cases. They do not necessarily extend to the nearest phloem, and sometimes pass round about through cortex, pith ray or pith, and in some cases are extending in phloem or xylem.

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In the first report, we mentioned the distribution and the abundance of the two pod borers of soy bean, Etiella zinckenella TREISCHKE and Grapholitha glycinivorella MATSUMURA, in Kanto District, with particular reference to their relationships to the annual average temperature. The mature larvae of both borers hibernate in soil. This paper deals with the relationship between their abundance and the soil type.
Surveys were made in 1957 and 1958, covering 88 soy bean fields of light, diluvial volcanic ash soil and of heavy alluvial soil in Saitama Pref., on the abundance of these pod borers. The borer's abundance was estimated based on the extent of damage of the pod. Examinations were also made from 1955 to 1957 on the extent of damage of the soy beans grown in the diluvial and alluvial fields belonging to the experiment station. Soy bean varieties of different ecological types were used in the examination.
It was generally found that the abundance of G. glycinivorella is much influenced by the soil type, and it is more abundant in the fields of diluvial soil. E. zinckenella, however, is little influenced by the soil type in the abundance. The former is less abundant in low land covered with heavy soil and of poor percoration of water where water stands after rain. It is fairly abundant in the fields lying on elevated places or on slopes and covered with loose soil which is well granulated, porous, and of good percoration and aeration. Even in the fields of heavy soil which is of low poresity, the borer is by no means scarce if the fields are located on the elevated places or on slope and are well drained. On the other hand, it is rather scarce in the fields covered with light soil but is ill drainable.
It may be concluded therefore that the abundance of the soy bean pod borer, G. glycinivorella, is affected not only by the soil but also by the topography and the amount of rain. In other words, the abundance is influenced by the complex local condition.

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Investigations were carried out to find out polyhedroses in some lepidopterous larvae. Nuclear polyhedroses were observed in Barathra brassicae, Plusia nigrisigna, Hyphantria cunea and Antheraea pernyi, but no cytoplasmic polyhedrosis could be detected. Sizes and shapes of these polyhedral bodies are shown in photograph (Fig. 1).
No cross-infection of polyhedrosis was observed among Barathra brassicae, Hyphantria cunea and Bombyx mori, although each species could be infected when fed with the polyhedral bodies of the same species.
When the larvae of Barathra brassicae and Hyphantria cunea were exposed to low temperature (5°C) for 1∼2 days or so, no polyhedrosis was induced. But polyhedroses were induced in Hyphantria cunea by feeding chemicals such as arsenic acid, merculic chloride, Phygon, EDTA (ethylene diamine tetraacetic acid) and sodium salt of EDTA.

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1. In order to know if there are any differences in physiological characters between the winged and the unwinged family lines other than the hormonal relations during the first nymphal instar of the winged line as supposed by me in the 7th report of this series, some comparative observations were made on the reactions to unfavourable life conditions such as overcrowding, feeding on deteriorated food leaves and starvation in the both family lines of two species of aphids, Rhopalosiphum prunifoliae in which the winged forms are readily produced from the unwinged mothers but not from the winged, and Macrosiphum granarium in which the winged forms are easily produced not only from the unwinged but also from the winged.
2. In Rhopalosiphum prunifoliae, the offspring born from the winged mothers are relatively indifferent to the freshness of food and have a great resistance to starvation in their own generation. But these chatacters disappear in the second generation. In the unwinged family line, the progenies become to possess also a marked degree of resistance to the unfavourable life conditions, after they grow to the third instar, whence the wing buds become visible.
In Macrosiphum granarium, these phenomena can hardly be recognized.
3. The appearance of the winged form seems to bear certain significances in the life cycle of Rhopalosiphum prunifoliae. In this, not merely the winged forms themselves are highly resistant to external factors since the later stage of their larval development but give rise to the next generation which possesses also a marked degree of resistance to unfavourable environmental conditions. In Macrosiphum granarium, the meaning seems to be confined only to the production of the form capable of migration.

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1. The effects of thiono- and thiolisomers of both demeton and methyldemeton on the activity of the nerve cord of the American cockroach and on the cholinesterase activity have been studied.
2. Both isomers of methyldemeton caused an increase in spontaneous activity and a prolongation of synaptic after-discharge, which were followed by a burst of discharges and a final synaptic block. These effects were reversible on washing with normal Ringer's solution when a weak concentration was used.
3. Both isomers of demeton exerted almost the same effect as that of methyldemeton, but differed in that the prolongation of synaptic after-discharge was preceded by a brief period of depression of postsynaptic response.
4. Four isomers all inhibited cholinesterase of the nerve cord in vitro, concentration for 50 per cent inhibition being of the order of 10^-6M.
5. The cholinesterase activity of nerve was half inactivated at the moment when spontaneous activity was increased and synaptic after-discharge was prolonged after treatment with demeton or methyldemeton.
6. It is concluded that the inhibition of cholinesterase is mainly responsible for the changes in nervous activity. Additional mechanisms are suggested for the action of demeton.

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