Epitrimerus trilobus is a mite that causes galls to form on the leaves of Elder. The leaf margin rolls upwards and becomes slightly thickened. The roll is 1 - 5mm wide, tight, short or extending around most of the leaf;  the leaf may be creased or buckled and reduced in size; the gall contains mites.

Aphids can also cause damage to the leaf, resulting in creasing and buckling.  

Adult Gall

The mite causes tight and narrow leaf-rolls; check for mites inside 

On the leaves of Elder.

Summer when Elder is in full leaf.

Thought to be widespread and fairly frequent in Britain, but probably under recorded.

Thought to be fairly frequent in Leicestershire and Rutland.