Phyllocoptes populi is a mite that causes galls to form on the leaves of Aspen and very occasionally on other members of the Poplar family. The gall has a distinctive yellowish bulge on upperside; the underside is an erineum with hairs that the mites live in between. The hairs below are pale at first, reddish or brown later, each broadened at the tip. The galls are seen more often than the mite.

 Aceria varia mites can cause erinea on the underside of aspen leaves, but with only a slight bulge above; the erineum hairs are also a different shape (pointed)

Gall Adult

Ensure that you have identified the host plant accurately.

On the host plants.

Galls in late spring and summer.

Fairly common and widespread in Britain.

Fairly common in Leicestershire and Rutland.