The European Corn Borer (Ostrinia nubilalis Hübner) is one of the major pests in Croatian agriculture. It is a pest that has spread to all regions of Croatia where corn is grown. It causes yield reductions ranging from 2 to 25 %, and even more in years favorable for its development. However, chemical control of the European Corn Borer is only carried out in seed corn and sweet corn. Properly determining the optimal timing and necessity for control at the right time is extremely important. Forecasting models are important components of integrated pest management strategies because protective measures must be timed to coincide with the key stages of pest development. They determine the optimal timing and justification for pest control in a specific area, requiring knowledge of weather data and pest population numbers. The ECAMON model is a multi-generational phenological model that predicts the development of the corn borer, assesses the risk of population establishment, and provides indications of climate-related stress factors. The aim of this thesis was to determine the dynamics of the emergence of the first-generation moths in cages with old corn stubble, establish the dynamics of moth appearance on pheromone and BISEX traps, determine the dynamics of corn borer presence in the field, and assess the level of damage. Based on the collected data, the reliability of the ECAMON forecasting model for predicting the European Corn Borer in northwestern Croatia was determined. The research results showed that the dynamics of the emergence of the first-generation moths can be successfully monitored using entomological cages with old corn stubble. Late placement of traps also influenced moth capture on traps, as well as the attractiveness of the bait used. The presence of the corn borer and damage in the field were assessed through visual inspections. The data obtained indicated damage caused by caterpillars, which increased during the monitoring period. Damage increased in parallel with the accumulation of effective temperatures. The effective temperatures at which the initial flight of moths, the appearance of 50 % of moths, and the appearance of 95 % of moths in entomological cages were determined and compared to the values from the ECAMON model. The data showed a slightly later appearance of the first generation of moths in the northwestern Croatia compared to the prediction of the first moth appearance based on the ECAMON model.