Galls are unique plant structures that emerge as a result of interactions with various organisms, mainly gall-inducing insects. These insects induce galls through a combination of mechanical and chemical stimuli, triggering the development of new plant tissues distinct from those of the host organ. The continuous stimuli provided by the gall-inducing organism are crucial for gall induction and development, and any alterations in the behavior of the gall-inducing insect can profoundly affect the structure and metabolism of gall tissues and the gall-inducing insect population dynamics. However, galls are integrated into a multitrophic context, reflecting a dynamic interplay between gall inducers, host plants, natural enemies, and environmental factors. In this context, parasitoids can exert significant effects on the control of the populations of gall-inducing insects, by reducing the outcome of their offspring. The inquilines can also have the same effect, reducing the populations of gall-inducers by indirectly killing them. These intricate interactions can also have profound consequences for the formation and development of gall structures, influencing gall tissue formation and development. Parasitoids manipulate the behavior and physiology of the gall-inducing insects, leading to changes in gall structure and metabolism. Inquilines, conversely, alter the shape and structure of galls by consuming plant tissues, prompting plant responses that may result in the formation of endogalls. This chapter delves into the impacts of natural enemies on the population, structure, and metabolism of gall tissues, prompting inquiries into the interactions between these natural enemies, the gall-inducing organism, and the gall structure.