Wasp Parasitic wasps Solitary life
 Some solitary wasps make galls, which are abnormal growths on plants. They form directly after the wasp lays its eggs, and the plant develops a growth around the egg, encasing it. The trigger for the gall to form is not known. The gall protects the eggs while they develop. Galls can be found almost everywhere in the late summer, especially on the branches of oak trees, like in this picture.