Y. Higa on various animals, parks and gardens in urban cities are suitable for the species. Distribution around houses When human-vector contact is estimated, a house is the smallest spatial unit. Therefore, studies to examine the blood feeding/resting place of vector mosquitoes, indoors or outdoors, is essential for the control of vector-borne diseases. There have been many studies on the feeding/resting place of dengue vectors. The density of Ae. aegypti is high indoors (endo-phagy/phily), while that of Ae. albopictus is high outdoors (exo-phagy/phily) [3, 38]. Why are Ae. aegypti and Ae. albopictus distributed in such way? As described above, high Ae. aegypti density in the indoor environment may be associated with the preference of the species for dark and moist places and for humans as a blood source. However, although the degree of preference may be differ between Ae. aegypti and Ae. albopictus, the latter species also prefers shaded and moist places in vegetation and has blood meals from humans. This indicates that the response of the two species is extremely different in the domestic environment. What is a house/building for Ae. aegypti and Ae. albopictus? In Thailand, the indoor and outdoor density of Ae. albopictus was examined using an experimental bamboo hut 2 × 2 × 3 m in size [32]. The wall of the hut was remov- able, and three types of wall were prepared, that is, walls with 25, 50 and 75% of the surface area open to the outside. In the experiment, there was no significant difference between the indoor and outdoor densities of Ae. albopictus with 50 and 75% opening walls. On the other hand, the outdoor density was significantly higher than indoor density with the 25% opening wall. The experiment clearly showed that walls were physical barriers impeding the entry of Ae. albopictus to a building. Higa et al. (2001) conducted the second experiment on Ae. albopictus in Nagasaki, Japan [32]. Net-walled build- ings (2 × 2 × 2 m) were built in an area with vegetation. In the buildings, the physical barrier was present, but the microclimate was similar indoors and outdoors due to the exchange of air through the net. Indoor and outdoor densities were examined, and temperature, relative humidity and light intensity were measured both indoors and outdoors. In addition, the density outdoors without vegetation was also examined. As a result, there was no significant difference in density between indoors and outdoors (with vegetation) or microclimate. However, density outdoor without vegetation was significantly low. The results indicated that the presence of vegetation was highly important for Ae. albopictus. Thus, we clarified that the lower density of Ae. albopictus indoors than outdoors is due to vegetation located outdoors and the 21 physical barrier presented by the walls of buildings. It was interesting to note that when a building was located in a vegetation area and microclimate indoors and outdoors did not significantly differ, some Ae. albopictus entered into the building [32]. At least three factors, i. e. physical barriers, presence of vegetation and microclimate, are associated with the exo- phagy/phily of Ae. albopictus. The degree of significance of each factor may depend on location, and the density seems to be an integrated consequence of the three factors. The behavior of Ae. aegypti and Ae. albopictus around houses/domestic environment is of special interest to the medical entomologist. The mark-release-recapture method is frequently used to understand this behavior. In this method, wild caught or laboratory-reared mosquitoes are marked with dye or material which can be traced, released in the field and recaptured at several sites over certain time intervals. Using this method, movement, dispersal and survival rate can be estimated. Previous studies have shown that the flight range of Ae. aegypti and Ae. albopictus is relatively small, usually within 100 m [3, 15]. However, it was also reported that the dispersal of dengue vectors was highly affected by the environment. In Puerto Rico, Reiter (1995) developed a method for marking Ae. aegypti eggs with a rare alkali metal (rubidium) and showed that the dispersal in urban areas was influenced by habitat avail- ability [62]. More marked eggs were detected from places distant from the release site when breeding sites were cleared. This study suggested that source reduction may enhance dissemination of virus-infected mosquitoes by reducing the number of available ovipositing sites. Horizontal and vertical dispersal of Ae. aegypti and Ae. albopictus was studied in apartment blocks in semi-rural and urbanized parts of Singapore [63]. From the results, it was concluded that females of both Ae. aegypti and Ae. albopictus could disperse easily and quickly throughout a radius of 320 m in search of oviposition sites. Releases on level 12 of a 21- storey apartment block, with ovitraps on each storey, showed a similar easy and rapid dispersal to the top and bottom of the building. The results contrasted with the general belief that Ae. aegypti seldom flies more than 50 m and that control operations can safely be based on such an assumption. In a village in China, Tsuda et al. (2001) released marked Ae. aegypti from different sites in the center and marginal area of a village and found that the distribution pattern of houses around the release site affected dispersal [64]. When marked females were released from a house in the center of the village, more females were recaptured inside the village, indicating that the females tended to remain in the village. In Thailand and Puerto Rico, Harrington et al. (2005) conducted 21 mark-release