The coffee berry borer is the main insect pest of the coffee and is one of the factors that contribute to the low yield of it crop, if the handling practices aren't made in the suitable moment. With the objective to determine the positioning and number of instars of the borer during the fruit development, was made a study in La Cumbre (harvests 2000-2001). Systematic samplings were made every 77 days post primary flowering (DPPF), collecting 25 fruits by repetition. It was observed that between a 70% until 86% of the borer that emigrated stayed in state of positioning B (susceptible) before the 112 DPPF. As of this date a noticeable reduction in the number of these was as it increased the age of the fruit, until staying low of 10% after the 147 DPPF. On the contrary the percent of borer in state of position D (reproduction) increased from 2 to a 57%. The number of eggs and larvae increased after the 112 DPPF from 0,2 eggs and 0,4 larvae to 2,8 and 3,9 by fruit, being respectively observed in this date the greater capacity of damage of these immature stages in the bean. An increase in the number of pupas by fruit was from 0,9 to 1 after the 119 to 189 DPPF.