Have you noticed these bright red nail like protrusions growing on tree leaves recently? Ever wondered what they are?
These could be spotted on a walk around your local Cambridge Nature reserve: Eriophyes tiliae, or more commonly known, nail galls occur on the leaves of our Large-leaved lime and hybrid common lime from now onward. They are caused by a leaf mite feeding on the sap of the leaves, this action causes chemicals to be secreted into the plant tissue and this causes the leaves to develop galls. The mite stays safe within the gall all summer growing and feeding from the plant cells which line the gall.
As the leaves die off in the autumn the mites exit the leaves from the underside and over-winter in the crevices of the bark or under bud scales from where they can easily access the new leaves in the following spring. Although the nail gall mite may disfigure the foliage it has little or no effect on tree growth.
Disfigure may be a strong word, adding interest and wonder may be better ones! Look out for these and other leaf galls as summer advances.
So the next time you wonder: what are the small red tubes growing a leaf called? You’ll know it’s caused by a leaf mite!