The cynipid wasp Diplolepis nervosa causes spiked 'sputnik' galls on the petioles, midrib or leaf blades of wild roses, usually underside but occasionally on the upper surface. 

It also forms smooth pea-galls, but these cannot be distinguished from those of Diplolepis eglanteriae.

Diplolepis eglanteriae

Gall  Adult

Anywhere that the host Dog-rose plant is found.

The adult insects emerge from their galls in spring.

Each gall is, in effect, a hollow, fleshy nursery chamber for a small white grub, the larva of the Diplolepis nervosa gall wasp, which feeds on the chamber wall. The galls appear to detach from the leaves before leaf fall and will lie in the leaf litter until the grub pupates and emerges as the small adult wasp, only about 4 mm long.

Quite common and widespread in Britain.

Fairly common in Leicestershire and Rutland.