A collection of thirty-six genetically diverse Pyrus genotypes were assayed for their effect on feeding by pear psylla (Cacopsylla pyricola Foërster) nymphs. The collection consisted of 27 P. communis L. clones originating from throughout Europe and selected clones of nine other species or interspecific hybrids of European or Asian origin. Ten 2nd or 3rd instar nymphs were placed on each of the top two fully expanded leaves of vigorous greenhouse-grown single-shoot plants. Each genotype was represented by 2 to 5 replicate plants. After 24 hours, the number of nymphs alive on the plant and the number actively feeding, as indicated by the production of honeydew, were counted. The distributions of live nymphs and active feeding were continuous within the collection. Analysis of arcsin transformed data indicated that there were significant differences among genotypes in percentage of live nymphs and percentage of actively feeding nymphs. The number of live nymphs present on the plants varied from 6 (30%) for P. ussuriensis PI 143978 to 20 (100%) for P. communis PI 312147. The percentage feeding varied from 5% for P. ussuriensis PI 312150 to 68% for the P. communis cultivar ‘Lesnaia Krasavitsa’. Although the two P. ussuriensis clones were among the most resistant, the numbers of live and feeding nymphs on cultivated and wild genotypes of P. communis were variable, ranging from highly susceptible to moderately resistant.