I see this every year. Any suggestions for the insect that causes it ?
No interactions present.
These 'Nail' galls are usually caused by aphids. The species of aphid is usually determined by the tree/shrub that they appear on. The leaves look like they might be Lime (Tilia), so the galls might be Eriophyes tiliae - the Lime Nail Gall.
Yes it is on Common Lime
Yes it is on Common Lime.
is actually a eriophyid gall mite rather than an aphid
Lat/Lng: 51.2, -0.5
OS grid ref: TQ0951