Class Arachnida (Arachnids)
Subclass Acari (Mites & ticks)
Order Trombidiformes (Trombid mites)
Family Eriophyidae (Gall mites)
Species Aceria aceriscampestris (Nalepa, 1922)
Gall height 1-3 mm.
This tiny mite produces pimple-like spots on the leaves of Field Maple (Acer campestre). Each pustule may contain several mites. The galls can be fairly prolific, covering leaves almost in their entirety. The mites leave the gall through tiny holes in the underside of the leaf in autumn and overwinter in fissures in the tree bark.
Seen summer through to autumn, and seen wherever the host tree grows. Common and widespread throughout Britain.
Local hedgerow, South Staffordshire. June 2013. © Peter Hillman.