Aceria cephalonea

Aceria cephalonea is a mite that causes galls to form on the leaves of Sycamore. The galls are red, less than 3 mm high and have a rounded apex. The galls are seen more often than the mite.

Aceria macrorhyncha

Adult Gall

Only on Sycamore.  Aceria cephalonea galls are small - less than 3mm - and with rounded tips.  Aceria macrorhyncha galls are up to 6mm tall, and with pointed tips.  Intermediates do occur, and these can't be identified from the galls.

Some indication of the size of the gall is helpful, and a close-up photo.  The host plant should be specified in the comments - e.g "Gall on Sycamore, 3mm high"

On Sycamore

Galls can be seen when Sycamore is in leaf.

Widespread and fairly frequent in Britain.

Fairly frequent in Leicestershire and Rutland.