AbstractSample sizes needed to measure population levels of the birch casebearer, Coleophora fuscedinella Zeller, and its damage to white birch, Betula papyrifera Marsh, were calculated for various degrees of confidence and assurance. Both a non-destructive and a destructive sampling plan are presented and a new method to classify the damage level of a stand. This method uses a maximum likelihood technique to estimate the proportion of trees of various damage classes.