Western flower thrips (WFT) Frankliniella occidentalis is a worldwide problem of various ornamentals and vegetables, especially under greenhouse. Here we present preliminary results of a study on spatial structure of a WFT population and its evolution over time on ornamentals under greenhouse. We used Spatial Analysis with Distances Indices (SADIE) methods to evaluate nonrandomness of the distribution and association of the distributions observed at different time. Spatial analysis of WFT population provided interesting information on the role of surrounding environment on the insect population inside the greenhouse.