Abstract: Crop protection in innovative and sustainable orchard management relies on precise timing of surveillance and control of pest populations. The system SOPRA has been developed as forecasting tool in order to optimize timing of monitoring, management, and control measures of insect pests in fruit orchards. Applying time-varying distributed delay approaches, phenology-models were developed driven by solar radiation, air temperature and soil temperature on hourly basis. Up to now, relationships between temperature and stage specific development rates for the relevant stages of the life cycles were established under controlled laboratory conditions for major pests of apple, pear, cherry and plum: Rosy apple aphid (Dysaphis plantaginea), apple sawfly (Hoplocampa testudinea), codling moth (Cydia pomonella), smaller fruit tortrix (Grapholita lobarzewskii), apple blossom weevil (Anthonomus pomorum), summer tortrix (Adoxophyes orana), pear psylla (Cacopsylla pyri), European cherry fly (Rhagoletis cerasi), red spider mite (Panonychus ulmi), and plum fruit tortrix (Grapholita funebrana). Insect body temperatures in the models are based on studies of habitat selection of relevant developmental stages and according simulations using the three driving variables and structural orchard features. For validation, model predictions were compared with independent field observations from several years. On base of local weather data, age structure of the pest populations is simulated and crucial events for management activities are predicted by the SOPRA system. Through a web-interface, the simulation results are made available to consultants and growers (www.sopra.info). As exemplified here, phenology is directly linked to a detailed decision support and to extended information about the pest insects as well as to the registered plant protection products. Fourteen climatic regions cover all fruit growing regions of Switzerland. SOPRA is applied as decision support system for the ten major insect pests of fruit orchards on local and regional scale in Switzerland and southern Germany and has a wide range of possible applications across Europe.