It causes a gall, which is a swelling on the external tissues, on the leaves of apples (Malus species).

The mite is found in Europe and was first described by the Austrian zoologist Alfred Nalepa in 1892.

The mites live and feed amongst minute, globular or wooly hairs on either side of the leaf, during the summer.

Infected leaves may fall in the late summer but the mites do not have a serious effect on the host tree.

During the winter the mites are dormant living in the buds or under loose bark.