Oak leaves in Spring

New oak leaves
New oak leaves

Our native oak trees (Quercus robur, Q. petraea) support the largest number of insect species of any tree species in Britain (1). Oak leaves emerge pristine and tender, but (like most of us!) become tougher and less nutritious as they age! These lovely virgin leaves are gradually colonised by leaf feeders in a regular seasonal pattern: first come the leaf chewing insects such as caterpillars in the Spring, then the sucking insects such as aphids, followed by leaf mining species in the summer; finally galls form on the leaves in late summer and early autumn (2). It’s remarkable that the leaves manage to do their job of photosynthesising for the tree, with all the hundreds of insect and mite species which rely on them for food!

References to classic studies by the late Professor Dick Southwood and co-workers.

1. Kennedy, C. E. J., and T. R. E. Southwood. “The number of species of insects associated with British trees: a re-analysis.” The Journal of Animal Ecology(1984): 455-478.

2. Southwood, T. RICHARD E., et al. “Seasonality abundance, species richness and specificity of the phytophagous guild of insects on oak (Quercus) canopies.” European Journal of Entomology 101.1 (2004): 43-50.

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