Hatching of eggs of Emmalocera sp. occurred during the day time, and was especially concentrated in the first half of a day. Fifty three day-degree (K_e), with a developmental threshold of 15°C, were required for hatching. The time of hatching was influenced by factors such as light-dark cycle (12L-12D), temperature cycle (30°C: 25°C) and endogenous rhythm. When the lightdark cycle or temperature cycle were controlled separately, hatching was concentrated in the light phase or high temperature phase, respectively, but if the two factors were combined, the hatching of larvae was observed only in the light phase. Hatching time was confined to a range of 50.6 to 61.8 day-degree in combination with light and dark conditions. The rate of hatching larvae boring into the stem was significantly higher in the light phase, suggesting that the light may be an important factor for stem-boring.

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Effects of temperature regime, stage of host plant and population density on population parameters and population growth of greenhouse whiteflies Trialeurodes vaporariorum feeding on tomato plants were studied in greenhouse experiments. Two types of temperature regimes were used: 30°C during day 20°C during night and 25°C during day 10°C during night. The survival rate in egg and larval stages was depressed after topping of mature tomato in the low temperature regime. Daily oviposition by adult females was not affected by temperature and stage of host plant. Mean lifespan was longer in the low temperature regime. Net reproductive rate was higher on tomatoes before topping than after topping. Intrinsic rate of natural increase was higher in the high temperature regime. The survival rate in egg and larval stages was not affected by population density. Daily oviposition by adult females decreased at times of high adult density.

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The analysis of soybean seed injuries caused by three species of stink bugs was carried out by releasing individuals among potted soybean plants. Damage caused by 1st and 2nd instar nymphs of Riptortus clavatus was not as severe as that caused by 3rd to 5th instar nymphs. Percentages of heavily damaged seeds were high in a plot where 4th instar nymphs and adults were released. The injuries caused by R. clavatus or Piezodorus hybneri were most severe at plant stages from middle podelongation to earlier seed-thickening. The total number of seeds injured by both males and females were almost the same for R. clavatus and Dolycoris baccarum, although the degree of injury were inflicted by the two species differed. Number of seeds injured by a single individual per day depended on the stages of R. clavatus and the stages of soybean plants. The number was largest when middle pod-elongation stages were attacked by female adults.

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Diapausing rates of a number of Tetranychus urticae populations occurring on various crops in Nara Prefecture, Japan were investigated. The diapausing rates varied among populations from different crops and populations from the same crops. Populations from rose showed the highest average diapausing rate (11.5%), while the second highest rate (8.5%) was for the populations from deciduous fruit trees such as pear and peach. The diapausing rates from chrysanthemum and eggplant were both 2.5%. T. urticae from strawberry, gerbera and spinach were almost exclusively of non-diapausing individuals. Significant differences were detected between the diapausing rates for T. urticae from rose and deciduous fruit trees (on which the mite populations can persist throughout the year) and from chrysanthemum, eggplant and strawberry (which are available for the mites for only a restricted period of the year).

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The daily periodicity of oviposition and predation of H. atratus on Laodelphax striatellus was investigated at 3-hr intervals under semi-natural conditions. The majority of oviposition and predation was observed during 6:00-9:00 and 12:00-15:00. It is presumed that the extent of oviposition was independent of ambient temperature and intensity of illumination. No oviposition and predation occurred during the night.

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Both in the laboratory and field, oviparous females laid most of their eggs in the area between the leaf scar and twig (near the location where buds would emerge in the following spring) of Hibiscus syriacus plants these sites are 30cm below the tips of twigs. Some eggs were also laid at a distance from the base of the buds in the scratched, hollowed out, or grooved branching off points of twigs. In view of the facts that buds could not yet be observed on the twigs in the ovipositing period in early November and oviparous females walked around extensively on the twigs, it was considered that oviparous females were searching for anything which was likely to serve as protection for their eggs, rather than searching specifically for buds.

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A simple method was developed to record the eclosion rhythm of the melon fly, Dacus cucurbitae, by weighing pupae using a computer-assisted balance. The number of adults eclosed was calculated by the decrease of weight of a batch of pupae. Data of the weight decrease of 30min. periods was entered into a personal computer (PC-9801 Vm2, NEC) and processed by an original program written in N₈₈ BASIC. Through this system, it was found that the melon flies emerged near the start of “light on” periods when the pupae had been subjected to a 12L-12D condition.

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The activity of the rice leaf roller, Cnaphalocrocis medinalis, was investigated using an electric actograph. Photoperiod and temperature conditions during larval and pupal stages showed no clear effect on the proportion of moving moths. The activity of males was similar to that of females. The activity of males reared on heading stage rice plants was slightly higher than that of males reared on rice seedlings, but it was not considered that the former showed higher flight abilities.

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The glass capillary formulation of the synthetic sex pheromone of Agrotis segetum was observed to catch the male moths effectively for 3 years, even though its attractive activity was reduced to ca. 50% after the exposure for 2 years.

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This is the first record of Metopolophium dirhodum (WALKER) in Japan. Small colonies of the species were found in the oat fields of Kitami Agric. Exp. Stn., Hokkaido, in middle August of 1988. At this time, most colonies were composed of apterous viviparae and larvae, and only a few alate viviparae were observed. In a culture of the aphid on potted plants of oat, an ovipara and some apterous viviparae were produced in early October together with many alate viviparae (? gynoparae) and alate males. The occurrence of apterous form on secondary host in autumn suggests that the population might include monoecious clones. In addition to the biometric data of the four morphs mentioned above, diagnostic characters were given to distinguish the present species from other cereal aphids in Japan.

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