There are silk button galls on the underside of oak leaves all over the park.
These are caused by the asexual, all female, generation of the gall wasp Neuroterus numismalis. The galls form on the oak leaves from August until October and each silk button contains a single wasp larva.
The wasp larva will mature in August but remain in the gall on the ground throughout the winter, emerging the following year from February to April.
Southwick Country Park Nature Reserve 