Two methods of investigation for the roof rat, Rattus rattus, in buildings were studied. Two types of rat signs, droppings and footprints on papers, at the entrances of ceilings were counted. The correlations of the number of rat droppings and the number of rat footprints on papers with the number of the captured rats were then investigated with regression analysis. As the results, the number of rat footprints on papers and the number of the rat droppings were found to correlate with the number of the captured rats. Therefore, the two methods are useful to estimate the number of the captured rats in a small area. It will, moreover, be possible that the number of rats in a restaurant is estimated by the densities of rat footprints if the number of the droppings from one rat per day is known.

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The usefulness of a method for quickly detecting mites in house dust with an adhesive lint roller was evaluated. The mean numbers of mites obtained were 29.5 mites/m² from tatami, 216.0 mites/m² from carpets, 249.2 mites/m² from bedding, and 110.0 mites/m² from closets. The correlation of the numbers of mites between the roller and conventional isolating method (vacuum cleaner with saturated saline) was significant (p<0.001) with a correlation coefficient of r=0.89. Repeated sampling from the same area seemed to reduced the nuber of mites that had not been caught. This novel detecting method was also useful for investigating the seasonal prevalence of the mite fauna. The lint roller was recognized to be useful for quick inspection of the mite population in an area.

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Insects in the green zone along a canal in Minato-ku, Tokyo, were investigated from June to October 2005. Many of the captured insects were wine flies of order Diptera in June and July. Most of the wine flies were Drosophila melanogaster and D. simulans, but D. immigrans, D. busckii and D. suzukii were also captured. Numerous ants of order Hymenoptera were captured after August.

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Mosquitoes were collected in Yokohama to clarify the seasonal and local distributions, as a part of the research to investigate the invasion of West Nile virus into Yokohama. CDC light traps combined with dry ice were set up to gather adult mosquitoes in each of 18 parks in 18 wards, three parks, and one public institution in the harbor area during the period from June to October 2005. The total number of mosquitoes was 6,546, and they were divided into 7 genera and 12 species. The dominant species captured was Aedes albopictus (49.6%), followed by Culex pipiens complex (34.4%) and Culex tritaeniorhynchus (7.6%). Culex pipiens complex was observed in each of 22 points throughout the research period, and the number of individuals exceeded those in the harbor area. In contrast, Aedes albopictus was collected mainly in parks of 18 wards. Most of the Culex tritaeniorhynchus were captured at Symbol Tower (park in the Naka Ward Honmoku harbor area).

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