Abstract.1. Field and published data reveal that there are at least twenty‐three species of phytophagous insects associated with Prunus padus L. in Britain. Most of these species occur on the tree between May and September. Interspecific competition does not appear to be severe.2. There are a total of 196 species of phytophagous insects feeding upon the various tissues of P. avium, P. cerasifera, P. cerasus, P. domestica, P. laurocerasus, P. padus and P. spinosa.3. A highly significant species (5)‐distribution (A) relationship of the form In (S+l)=0.92 In A‐2.19, was obtained for the Prunus species examined within Britain (excluding Ireland), i.e. the wider the distribution of the plant the greater the number of insect species associated with it.4. However, critical analysis of the data indicate that P. padus does not support as many different insect species as expected.5. Neither plant form nor age of establishment within the British Isles accounted for this discrepancy.6. The possibility of using a plant's insect fauna to describe its relationship to other plants in the same genus is disc