Small spangles

If you find an oak leaf that is covered with something that looks like small, flattened lumps of green- and red-spotted cake batter, or maybe plasticine, then you have found some galls from the spangle gall wasp. The small, flat galls,are attached by a tiny stem on the underside of the leaves. Here they stay throughout the whole season, until the leaves fall off the trees, taking the galls with them, or the galls break off and fall onto the forest floor where they overwinter until spring. The new wasps then come out, ready to start the whole process from the beginning, when the oak leaves shoot.

Try and pick a spangle gall off an oak leaf. Sometimes you will find one or two small orange larvae under each gall. These are larvae from the Parallelodiplosis galliperda midge. It isn’t a direct parasite of the spangle gall wasp larvae, but it chews on the galls from underneath, which can mean there is not enough food for the wasp larvae to become adults.