Öz
Forests tend to disappear for various reasons. Insects have problems such as very high reproduction and spread rates, unpredictable distribution directions, and inability to intervene quickly in the fight against insects. For this reason, harmful insects are at the beginning of many factors that cause forest loss. For the study, Bursa-İnegöl Tahtaköprü location, which was affected by the red-tailed beech caterpillar (Calliteara pudibunda) affecting beech trees, was determined as the study area. This study was carried out on the Google Earth Engine (GEE) interface. For the study area, using Sentinel-2A and Landsat-8 satellite data for the period 2017-2021, 6 different plant indexes; NDVI, EVI, SAVI, RVI, TVI, NPCRI were calculated and it was determined that the most affected period from pests was October 2019. These indices were also calculated for October 2019, and classification was made for four different data combinations in 5 different classes (diseased, healthy, road, power line, settlement) using the Random Forest Classification Algorithm and Support Vector Machines methods, which are machine learning-based classification methods. The classification result was compared for Landsat-8 and Sentine-2A, and the best result was the combination including all plant indices for Sentinel-2A satellite data, and the overall accuracy was calculated as 98.48 and the kappa coefficient as 97.68.