The modification of plant structures through hypertrophy and/or hyperplasia leads to the development of galls that can be induced by various biotic agents such as viruses, bacteria, fungi, algae, nematodes, rotifers, copepods, and insects. Galls provide better utilization of underutilized niche, thus they have been reported to be helpful for insect survival and evolutionary processes. Around 13,000 species of gall-inducing insects are known worldwide, representing about 2% of the total number of insect species. These insect- gall inducers belong to different families of Hemiptera, Thysanoptera, Coleoptera, Hymenoptera, Diptera, and Lepidoptera. Even though, their wider distribution throughout the world, they have not yet explored fully. The plant defense – insect offense interaction in the gall- host interaction depends on various factors such as the production of effectors, the release of phytohormones, indirect and direct plant defense mechanisms that need to be studied for better understanding. There is a need to decipher the mechanism of gall induction to manage the insects economically.