Tim location of an herbivorous insect on its host plant can tell us much information about its ecology. For example, KENNEDY et al. (1950) noticed that the sucking site of Myzus persicae was quite different from that of Aphis s and they then inferred the importance of sap nitrogen concentration for M. persicae. More recent examples include J~.esoN's (1983) study on M. persicae movement in relation to leaf aging physiology. The population dynamics of the green rice leaf hopper (GRL), Nephotettix cinctictps (UHLER) (Homoptera: Cicadellidae), has been well studied in Japan. A major feature of its population dynamics is a density dependent process which stabilizes late season population density (KuNo, 1968) at least in western Japan (KIDOKORO, 1979). It is not yet clear what the actual density dependent mechanism is, but two possibilities are 1) direct interference between individuals at high GRL density, and 2) GRL density mediated changes in host plant quality. Another characteristic of the GRL, which may play an important role in its population dynamics, is that its population parameters change with varying rice plant quality. When given well fertilized plants, the GRL survives better, develops faster, and reproduces more than on unfertilized plants in the laboratory (OvA and SuzuKI, 1971). It also prefers normally fertilized plants to underfertilized plants, and in the field, populations increase faster and attain higher densities on normally fertilized paddics than on underfertilized paddies (D. A. ANDOW, unpubl, data). Although much is known about the population dynamics, rather little is known about the microsite of the GRL. This information may give insight to the mechanisms leading to its observed population dynamics. So in this paper, I will show how changes in nitrogen fertilizer and GRL density affect the microsite and dispersion of the GRL on rice, and develop an hypothesis for why these effects occur. In addition, I will present data suggesting that the density dependent population regulation mcchanism of the GRL may be related to decreased host plant quality at higher GRL densities.