Host plant associations, diversity and species—area relationships of mesophyll‐feeding leafhoppers of trees and shrubs in Britain

. 1. Sixty‐two British species of Typhlocybine leafhoppers are known to feed on the leaf‐mesophyll tissue of trees and shrubs. British host records for fifty‐five of these are given. 2. The leafhopper faunas of thirty‐six species of native and introduced trees and shrubs are described. 3. The Shannon‐Wiener equation was used to calculate species diversity for adult samples collected from twenty different species at sixteen different localities in Wales, southern England and northern Scotland. 4. Sørensen's coefficients were calculated for rearing data from Britain generally, and subjected to cluster analysis. Most trees have low similarities with respect to leafhopper faunas and are quite distinct. Taxonomic relationships of trees appear to be relatively unimportant in determining the similarities of their leaf‐hopper faunas. 5. Using the same data, species—area relationships were calculated for thirty‐four different tree and shrub species and their associated leaf‐hoppers. A significant regression was obtained, but it explained only 16% of the variation. It is thus suggested that host plant range is relatively unimportant in determining the numbers of these species associated with different trees in Britain. 6. Some introduced species of trees, particularly the recently planted Nothofagus , have acquired large leafhopper faunas.