The mouth parts, their accessory organs, and the penetration of stylets into the host plants have been studied in Aphis craccivora KOCH on several species of host plants. The aphids feeding on host plants were suddenly paralyzed with ethyl ether, and plant portions with aphids were fixed in BOUIN'S fluid for 5-10 hours. Paraffin sections, 15μ thick, were stained with DELAFIELD'S hematoxyline, safranin T and acid fuchsin. The main results are summarized as follows:
(1) Food meatus is fine, and hypopharynx is thickened, sclerotized and is bound with maxillary stylets on each side and at this part food canal of the stylets is connected with food meatus, and salivary canal is with salivary meatus.
Cross section of well developed sucking pump is nearly pentagonal in shape, and the posterior side much sclerotized, but the anterior side membraneous. Dilator muscles arising from clypeus attach at the center of the anterior side.
(2) Salivary glands are in four pairs, namely principal, accessory, mandibular, and maxillary one. According to MILES (1959), Aphis craccivara KOCH secretes two kinds of saliva, a highly viscous secretion and a watery liquid. The former is used for sheath formation and seems to be secreted from the mandibular and maxillary glands, while the latter from the principal and accessory glands.
(3) Rostrum (labium) is shortened when stylets are inserted into plant tissues. The first segment of rostrum is pale, thin-integumented and flexible. The second segment is longer than the first, smaller in diameter, and more sclerotized, and can be telescopic within the first segment. The base of the second segment reaches the oesophagous ganglion when the stylets are inserted deep into the host plant tissues and the second segment of rostrum is much drawn within the first segment.
(4) The courses of stylets in plant tissues are different in some respects among different host plants. The stylets usually take a roundabout way to avoid mechanical tissues, but occasionally pass intercellularly through this tissue. They usually extend to phloem, but were commonly observed reaching the xylem, or the parenchyma of cortex on Phaseolus angularis WIGHT. The stylets or stylet tracks are found more times in the imperfect lignificational xylem than in the perfect one.

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Control failure of Panonychus ulmi (KOCH) with the application of Phencapton (0, 0-diethyl-5-(2, 5-dichlorophenyl mercapt methyl) dithiophosphate) was observed in the apple orchard of Tohoku National Agricultural Experiment Station, Fujisaki-Machi, Aomori Prefecture, in the seasons of 1959-'60, where this chemical had been introduced in 1957 and the initial application had given good result.
In September 1960, the mite population from the control failure tree (Ph-population) was compared in laboratory with a population (M-population) derived from a garden at Zaifu-cho, Hirosaki city, where no chemical had been used. The concentration-mortality tests were made with Phencapton and Folidol (diethyl-p-nitrophenyl thiophosphate) on the samples from these two populations. The resulted LC50 values with each chemical application to Ph-population were 95.35 and 4.45 times of M-population, respectively. Thus, these two populations were extremely different in susceptibility to each chemical; Ph-populations showed marked resistance to Phencapton and cross resistance to each chemical. The slope of logarithmic concentration-mortarity regression line of Phencapton to Ph-population was steeper than that to M-population, while of Folidol the reverse was observed. This may be attributed to their difference in the mode of acaricidal action.

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For the foundation of the research on the compound eyes of the aphids, the author has reported on the structure and the development of a few gall aphids and root aphids. The present paper deals also with the outer structure and composition of compound eyes in hatching larvae. The larval eyes have been studied in 18 species of aphids belonging to 15 genera. The results are summarized as follows:
The compound eyes are divided into three groups. The first group comprises Astegopteryx distylii, Ceratovacuna nekoashi, Dryopeia nishiyae, Tetraneura ulmi and Anoecia corni. Each species have 3 facets, the diameter of hind facet is 8∼11.6μ, dorsal facet 8∼10.8μ and that of abdominal facet is 8∼10.4μ.
The second group comprises Lachnus tropicalis, Chaitophorus saliapterus, Aphis pomi, Myzus persicae, Toxoptera piricola, Macrosiphum rosae ibarae, Macrosiphum sp., Aphis gossypii, Periphyllus californensis and Periphyllus sp. Ocular tubercle is consisted of 3 facets and compound eye 5∼58 facets. The diameter of facets is as follows; hind facet 12.4∼20μ, dorsal facet 10∼16μ, abdominal facet 10∼15.2μ and compound eye facet 8∼12μ.
The third group comprises Capitophorus hippaphaes, Eulachnus thubergii and Cinera pinea. They have no ocular tubercle but compound eye is consisted of 16∼40 facets, the diameter of those facets is 8∼12μ.

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In this paper the relation between the feeding activity of the prehibernant adult of the lesser clover-leaf weevil, Hypera nigrirostris, and temperature was dealt with.
Total amounts of food consumption by the adult, during the prehibernation, are nearly equal under the temperatures, 10°, 15°, 20°, 25°, and 28°C.
The duration of feeding is shortened according to the rise of temperature.
Under higher temperatures such as 20°∼28°C the feeding activity of the adult for the first seven days after emergence is very active, but declines rapidly with the lapse of time.
While under a lower temperature such as 10°C the feeding activity of adult is invariable through the duration from emergence to hibernation. The death rate of the adult under 28°C reached 50% in these experiments.
From these results the temperature zone of the feeding activity of the adults is in the range from 10° to 28°C, and it appears that the optimum temperature of the activity is in the range between 15° and 20°C.

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The fluctuation of adult emergence at regular intervals was observed, when the population of the almond moth, Ephestia cautella, was bred under a constant physical environment with the periodical supply of rice-bran (TAKAHASHI, 1953).
In this experiment, the influence of the time interval of food supply upon the mode of adult emergence was examined. Four populations were bred with the food supplied at intervals of 10 days (Populations A and B), 20 days (Population C), and 40 days (Population D), respectively, under the constant environmental condition.
In Populations A and B, the peak of emergence occurred periodically at intervals of about 35 days. This fluctuation might be caused by the periodical occurrence of the destruction of the individuals by the direct interaction among individuals of di f-ferent ages (TAKAHASHI, 1959b), especially by the larval cannibalism to the eggs and the pupae. The length of a period of this fluctuation coincided with the length of the life cycle, so this fluctuation can be interpreted as the sequence of emergence in a population in each generation. Therefore, the repeated introduction of eggs at the starting point of the experiment and the frequent supply of food at a short interval would not build up a stationary age distribution. But, when the length of interval of food supply was longer than the length of the life cycle of an insect, the shortage of food occurred before the next food supply, so the fluctuation of adult emergence corresponded to this longer interval of food supply, as was seen in Population D.
When the population in each generation was computed from the number of emergent adults as mentioned above, it maintained a steady state from the second generation in Populations A and B. The population trend of Poplation C was similar to those of Populations A and B, excepting an overshooting growth of population in the second generation. In Population D, the population fluctuated violently.
The reproduction curves drawn from the census data of the four populations were different in their shapes. The curves of Populations A and B were the saturation type, while Population C took the mountain shaped curve. In Population D, the points represent the relation to the reproduction curve, but they were not distintinct. They rather seem to be the mountain shaped curve. These differences might be due to the different modes of population regulation among the four populations as mentioned above.

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There are many reports on food plants of the vegetable weevil, Listroderes costirostris obliquus KLUG. However, there is no complete list hitherto in which food plants are classified into families. In order to obtain a basic knowledge of food habit in this insect, the author collected the records of food plants and arranged them in two tables (Table 1 & 2). The survey of literatures pertaining to this list was concluded in March, 1961. The importance of the publication of such a list for plant protection needs no emphasis. The list indicates the following characteristics of food habit in this insect.
1) The food plants of the vegetable weevil amounted to total of over 34 plant families, 178 species (including varieties). In Japan, 26 families 97 species (including varieties) were reported.
2) All of these food plant families belong to Dicotyledon, with only one exception of Liliaceae.
3) In the list, Compositae takes rank as the first in number of species (including varieties), Cruciferae as the second, and Umbelliferae as the third, followed by Caryophyllaceae, Leguminosae, Polygonaceae, and Solanaceae.
4) If the plants which were recorded as food only by experiments are excluded, Compositae still ranks first, Cruciferae second, and Umbelliferae third, followed by Solanaceae, Leguminosae, Caryophyllaceae, etc.
5) 19 families 66 species of the food plants are wild plants, while 8 families 13 species are ornamental plants, and 12 families 56 species field crops. In wild plants Compositae takes the first rank, and in field crops Cruciferae.
6) In comparison of report frequencies represented by the number of prefectures from which the damages of particular field crop were reported in Japan, the top is Cruciferae, the second is Umbelliferae, the third is Solanaceae, Chenopodiaceae, and the fourth is Compositae.
7) It may be concluded, at least in regare to number of food plants and report frequencies, that Cruciferae, Compositae, Umbelliferae, and Solanaceae are important food plants of the vegetable weevil. In fact, these plant families contain the plants which are severely damaged by this insect.

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This experiment has been carried out in order to rear the rice stem borer, Chilo suppressalis WALKER, through successive generations with artificial diets under the aseptic condition. The results obtained were summarised as follows:
1. An improved diets contained high amount of choline chloride to obtain normal moths, and the moths deposited fertile eggs through five generations under the aseptic condition.
2. Of the experiments following two kinds of diets seemed to be suitable for rearing the rice stem borer.
3. There was few difference between this borer reared on the two kinds of diets and those on rice plant in the paddy field in the weight of matured larvae, rate of pupation and number of egg masses layed.
4. Though the number of normal female and of normal eggs were increased by the improved diets containing high amount of choline chloride (0.2-0.3g per 200ml of Erlenmeyer flask), the results obtained were not sufficient compared with that of wild one.
5. When the wild male mated with the female reared on the artificial diets, the rate of egg hatching was increased in some grade. But this increasing of the rate was decreased in the next generation.
6. From the results in this experiment, it is expected that Shonai-ecotype of this insect can be reared for about 10 generations and Saigoku-ecotype 6 generations in a year under non-diapause conditions on the artificial diets.

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Diapause in Carposina niponensis occurs at the end of the larval stage, and the diapause larva spins the characteristic winter cocoon. In the field, few larvae enter diapause in July, but a number of diapausing larvae begin to appear from the beginning of August, and thereafter the percentage diapause increases regularly towards the end of that month, when almost all larvae enter diapause on maturity. The transition in the growth pattern of the larvae from non-diapause to diapause thus occurs at about the middle of August.
In the laboratory, the onset of diapause was readily controlled by light hours per day artificially applied during the larval feeding stage. Namely, at 21°C the larvae averted diapause only within a narrow range of photoperiod lasting from 15 to 18 hours per day, and the incidence of diapause was increased by either a longer or a shorter photoperiod. In darkness the occurrence of diapause was suppressed to a certain extent by a temperature as high as 30 or 33°C, while diapause was prevalent at a temperature of 25°C, or lower. The larvae were sensitive to both day-length and temperature during the entire feeding stage, and there could be recognized no particular instar critical for the induction of diapause.
When diapausing larvae were constantly kept at a temperature of 20°C, or higher, most of them could not emerge from their winter cocoons and failed to pupate for a long period. Previous exposure to a low temperature between 5 and 15°C promoted the emergence from winter cocoons and the subsequent metamorphosis. The diapausing larvae required about two months at these temperatures to terminate diapause, but a temperature close to the freezing point was found to be detrimental for the larvae.
From these results of field and laboratory tests, it is concluded that the length of day might be the principal factor governing the onset of diapause in the field.
Possible occurrence of local differentiations in the diapause behaviour of Carposina niponensis is discussed to a certain extent in view of the available information on the phenology of this orchard pest in various localities.

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[in Japanese]

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[in Japanese]

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The penetration of α-, β- and γ-isomers of BHC through insect cuticle has been studied in order to find why only γ-isomer has a high insecticidal potency among the isomers. BHC-1-C¹⁴ isomers were topically applied on the male Amrican cockroaches Periplaneta americana, and radioactivities recovered from “outside” and “inside” were determined at 1.5, 6 and 24 hours after the treatment. The γ-isomer penetrates more easily than the other isomers, α- and β-isomers following in decreasing order. The rapid and easy penetration of the γ-isomer through the insect cuticle is believed to be an important factor for its insecticidal potency. It is considered, however, differeneces of certain biochemical changes among isomers which will be taken place after the penetration through insect cuticle are more importance to solve the mode of action of BHC isomers.

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