Abstract: Outbreaks of the Oriental migratory locust, Locusta migratoria manilensis(Meyen) have once again become a serious problem in the last two decades of the 20th century in China. One of the coastal breeding areas of the locust, Nandagang reservoir of Hebei Province was chosen as study area in this paper. Against the background of the locust outbreak (summer locust) of this area in 2002, spectral reflectance curves of reeds for different damaged degrees (heavy, moderate or no damage) were measured and determined. The results showed that healthy reeds manifested the “peakandvalley” configuration as that of other healthy green vegetation. But for damaged reeds the red reflectance increased, and the heavier the damage, the higher the red reflectance values, whereas the reflectance in the near infrared bands decreased dramatically with the damage scalating. Additionally, the locustdamaged areas and degrees were determined using MODIS data. Comparisons of NDVI changes between pre and postdamage showed that the increase for the same site in NDVI relative to the predamage situation corresponded to the undamaged areas whereas the decrease in NDVI corresponded to the damaged areas. Coupled with the ground truth data, critical values of NDVI for heavy and moderate damage were determined as 0.2156 and 0.2389 respectively. Namely, areas with NDVI less than 0.2156 were identified as with heavy damage; while areas with NDVI less than 0.2389 as with moderate damage. By calculating the numbers of pixels, areas discriminated from MODIS images as with heavy and moderate damage were 168.74 hm² and 337.48 hm² respectively, with 72.97% and 68.35% accuracy respectively evaluated by the ground truth data. The total damaged areas identified from MODIS data amounted to 82.67% of actual occurrence areas. These findings contributed to the scientific foundation for quickly monitoring the dynamics of locust populations in real time and at large scale and efficiently controlling locust plague.

Key words: Locusta migratoria manilensis; locust plague, remote sensing monitoring, spe ctral data, MODIS data, NDVI, ground truth