SUMMARYThe majority of Epitrimerus piri on pear, cv. Williams' Bon Chretien, moved from their hibernation sites in small permanently dormant buds on spurs and under loose bark to fruit buds between the stages of green cluster and petal fall. Peak numbers of mites occurred in mid‐June on fruit and early August on leaves with the return to hibernation beginning in July. Development time from egg hatch to adult was 17–1, 6–9 and 4–8 days at 10, 16 and 22 °C, respectively. Mites were dispersed by wind. They were found only on species in the genera Pyrus, Cydonia and Pyronia.Mite feeding caused browning on the ventral, sides of leaves and russet on fruit which was confined to the calyx end on Williams'. Populations of over 2000 mites/leaf reduced the length and dry weight of new shoots on potted pears by 8 and 14% respectively.