This report concerns the effect of insecticide-impregnated paper sheets on the market against house dust mites, Dermatophagoides farinae. Four kinds of the sheets impregnated with phenothrin or permethrin were tested in the laboratory. The suppression rates of population growth were 0 to 8.4% and 2.3 to 36.1% after 2 weeks and 4 weeks, respectively when the initial mite density was 37 individuals in 0.2g feed, and the rates were 10.6 to 35.9% and 27.2 to 64.2% after 2 weeks and 4 weeks, respectively when the initial density was 274 individuals. The sheets impregnated with permethrin were more effective than those impregnated with phenothrin, but were incompletely effective.

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The effect of one-day exposure of gravid females to a toxic bait tablet was examined. Both the bait tablet containing 20% boric acid and that with 2% hydramethylnon resulted in 100% kill of the cockroaches within 11 days and 5 days, respectively. Lack of drinking water resulted in 100% mortality of cockroaches within 8 days. Although more than 50% of oothecae hatched when the parent females were given drinking water only, the females died before producing the next oothecae, and the rest females died leaving or holding the current oothecae dead. These results indicate that 100% of the females can respond to an attractive toxic bait in a single day, perhaps responding to the new kind of aroma and taste of the bait. The results also show that water and food supply to gravid females is necessary for 100% hatch of their current oothecae.

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Under 28-34℃ and 12L-12D conditions, females started egg-laying 6-20 days after their emergence into adults, and the number of eggs laid by one female abult ranged from 61 to 259, averaging 148.8. The male and female abults were still alive on the 50th day when the experiment was abandoned, though the females had laid no eggs during the last 7 days. At 23-25℃, male and female adults survived for 89.8 and 112.2 days, respectively in average, and the mean number of eggs laid was 58.8per female. When chilled at 4-5℃, eggs were killed within a week, fully-grown larvae and pupae survived for less then 16 weeks, and other stages could not tolerate 8 weeks.

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The harbouring hehaviour of adult German cockroaches was experimentally studied using two slit shelters vertically stood in each test container. The utilizable inner space of each shelter was 10×10×0.5cm. When 22 or 28 adults were released in one container, ungravid females splited into two shelters, in the same way as males did in previous experiments. The value of nearest neighbour distance (NND: in mm), however, was smaller, and the highest peak in the distribution of NND was not so clear as that of males. When the same number of males and ungravid females were mixed in a container, they also went into two shelters, even though the minimum group size of 16 cockroaches were used. When gravid females, ungravid females, and males were mixed, the mixed population splited into two shelters. However, the number of cockroaches in one of the two shelters swelled with greater aggregation, and that in another did not though the number of tested insects was increased.

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Abrupt decrease in larvae and imagines of Chironomus yoshimatsui was observed in resent years, although their increase had continued until 1991. The decrease of C. yoshimatsui is caused by clarification of the Nikaryo-yosui as a main habitat of the midge larvae. In accordance with the decrease of BOD (biological oxygen demand) to less than 10mg/l, the sampled midge larvae from mud bottom and the imagines caught by the light trap diminished to 1,000per 100cm² or less and 10per one light trap or less in mean number, respectively. The complaint and consultation about the midge decreased accordingly.

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We examined the anti-invading effects of covering houses with screen nets treated with cyphenothrin against Halyomorpha mista and Menida scotti. High preventive effects (92.0〜97.9%) for small wooden houses were obtained through these methods. It is supposed that the cyphenothrin net effeetively prevent the bugs from invading the dwelling houses, offices, workshops and accomodations.

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The movement of adult German cockroaches was examined by a mark-recapture method in a Japanese restaurant. The restaurant was approximately 68m² (9.7m×7.0m) in area, located at the basement floor. Plastic case traps were used for live capture of cockroaches, and live captured adult males and adult females (ungravid and gravid) were marked and released. Sticky traps were then used for recapturing cockroaches.
When the adult males and ungravid females were released at the entrance of the restaurant, they were recaptured mostly near the kitchen. This movement was most likely for foods and water.
When they were released in the kitchen and the smoking agent was applied on the day to the release, most of the recaptured were near the release point. They only moved a short distance in a day.
Gravid females were always recaptured at the point close to the release point.

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The influence of competitive food, Hamster Food (Nihon-haigo Oriental Animal Food®), on the efficacy of a cockroach tablet, Maxforce®, was examined using experimental populations of the German cockroach, Blattella germanica (L.). When the distance from the harborage shelter for cockroaches to a bait tablet (5g) was 17cm, two, four or eight pieces of competitive food totally weighing the same as the bait tablet, did not reduce the efficacy of the bait against male adults. The competitive food, however, increased the time to kill female adults, depending on the number of pieces scattered around the harborage shelter. When only one piece of competitive food was placed just beside the bait or the shelter, or halfway between the bait and the shelter, the position of the food did not affect the efficacy of the bait of 17cm distance from the shelter. When a barrier plate with a hole of 1.0×0.5cm square as a passage opening was set between the cockroach bait and the harvorage shelter, even a single piece of competitive food placed on the shelter side greatly reduced the efficacy of the bait against both male and female adults.

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[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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