Have you even been exploring and wondered what those funny lumps and bumps are on the leaves and trees are? Well they might well have been galls!

Galls are growths that are caused due to associations with other organisms such as midges, sawflies, mites, fungi, wasps and others! Galls can be all different colours, shapes and sizes and the ones we have been looking for are Silk Button Galls and Spangle Galls! Both types of galls are caused by wasps and in particular, female wasps.

The Silk Button Gall is produced by an asexual generation of solitary female wasp called Neuroterus numismalis and gets its name due to its appearance looking like its covered in tiny golden silk like hairs, looking just like a silk button (this is where our wasps a -silking comes in). The sexual generation of these wasps produce a different gall that look like blisters on the leaves.

Often found next to the Silk Button Gall is the Spangle Gall, which look like tiny flying saucers, and these can completely cover the underside of leaves and are created by a species of solitary wasp called Neuropterus quercusbaccarum. The sexual generation of this species of wasp again produces a completely different type of gall that look like currants hanging from the tree’s catkins.

Waiting inside their saucer like home, the galls will fall off from the leaf and they can often be spotted in great numbers on the ground under oak trees in the autumn. They will then become covered by leaf litter where they will spend their winters.

We think galls are fascinating and great fun can be had exploring the leaves, seeds and nuts of trees throughout the year. We managed to find Spangle Galls on Oak leaves when we went exploring in Christchurch Park, but our search for the Silk Button Gall continues! Why not have a look for Silk Button Galls and Spangle Galls this winter and see if you can spot any?