Spectacular year for oak leaf cherry galls

 I don't think I can recall a year when oaks hereabouts have hosted so many different kinds of galls, in such abundance. These oak leaf cherry galls, caused by the cynipid wasp Cynips quercus-folii, are growing on an oak near Blaids wood, just south of the city of Durham.

There will be a single gall wasp larva inside each, which will pupate and then emerge in late winter as a mature wasp, after the gall has spent the winter in the leaf litter.

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Sharing a leaf with a severe infestation of silk-button galls caused by Neuroterus numismalis, and a single pea gall caused by Cynips divisa

Sharing a leaf with spangle galls caused by Neuroterus quercus-baccarum

Plant galls

This is probably the best time of year for anyone interested in plant galls - those strange growths on plants caused by insects, mites and sometimes fungi. These are a few that I've seen locally over the last couple of weeks.

Leaf petiole of common lime Tilia x europaea with a gall chamber containing larvae of the gall midge Continaria tiliarum.

Ash flowers galled by the ash gall mite Eriophyes fraxinivorus.

An old oak apple gall caused by the gall wasp Biorhiza pallida, with exit holes where the adults have hatched.

Silk button galls on the underside of oak leaves, containing larvae of the gall wasp Neuroterus numismalis

Spangle galls on the underside of an oak leaf, containing larvae of the gall wasp Neuroterus quercus-baccarum.

Galls on leaf surface of sycamore caused by the eriophyid mite Eriophyes macrorhynchus aceribus. Click here for pictures of eriophyid mites.

Bean gall in the leaf blade of willow, containing the larva of the sawfly Pontania proxima

Robin's pin cushion or bedeguar gall on wild rose, caused by the gall wasp Diplolepis rosae. 

For pictures of the gall wasp click here. 

For pictures of the parasite that attacks the wasp, click here.