Abstract: Based on the two migration events of Nilaparvata lugens(Stal) population, which had led to its serious infestation on rice in Changjiang valley, the main ricegrowing regions in midsummer of 1991，and introduced into certain physiological and ecological parameters controlling the migration， a dynamical and numerical prediction model with higher spatiotemporal detectablity——MM4 and a means of calculating for 3-D trajectory were used to model the dynamic state of their migrating northward . The simulations and the comparisons between the simulations and the practical pests investigation showed: (1) The emigrating resource was an area from 22.5°N to 27°N on latitude and from 110°E to 116°E on longitude. (2) There were three spatial migratory paths, which consisted of a main path with an azimuth of about 32° and two assistant paths of about 10° and 75° respectively on azimuth.(3)There were three immigrating and descending regions with a main region situated in the middle and lower reaches of Changjiang valley, an assistant region joined northwestern Hubei with northeastern Sichuan and another assistant region enclosed southeastern Zhejiang and northern Fujian.(4)The conformity between the simulations and the practical pests investigation just illustrated that this model is an important means for the exploration of migratory pests' catastrophic mechanism.

Key words: Nilaparvate lugens(Stl) migration, dynamical and numerical simulations, 3D trajectory analysis, migration parameters, catastrophic mechanism