EN
In 2006–2009, a field experiment aimed at assessing the reliability of forecasting the development of Colorado potato beetle population with the use of decision support system SimLep 3 was carried out. SimLep 3 simulates Colorado potato beetle population development, based on the measurement of air temperature and results of field observations made at the beginning of egg deposition period. It was stated a complete confirmation between forecasted dates and real dates of egg maximum abundance, and the highest intensity of young larva infestation. Small differences between forecasted and real date of L1 and L3 appearance did not affect the usefulness of SimLep 3 system for effective potato crop protection against Colorado potato beetle.