This research aims at reducing the use of chemical insecticides in field vegetables (mainly cabbage and leek), by predicting the occurrence the pest insects. The final aim is to minimize the impact of the insecticides on the beneficial fauna andthe environment. Example: during the last 6 years we monitored the development of Thrips tabaci throughout the year on several location in Flanders, in order to get a clear view on their population development and migration; this enabled us to reduce insecticide input in leek by 50-60%.